Category Archives: 76 turret

#64 Sherman Fire Control: How the Gun Was Aimed, not Putting Out Fires!

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Sherman Fire Control: How the Sherman aimed its Main Gun.

The Sherman tank went through a series of fire control changes each an improvement over the last.  The first tanks lacked telescopic sight mounted on the gun mount. The only site was incorporated into the gunner’s periscope, and it wasn’t magnified. Since the periscopes were all interchangeable, updating the older tanks was easy at least were the periscope was concerned.

The final fire control setup the Sherman gunner had at his disposal was pretty impressive by the standards of the time. He was in a hydroelectrically driven turret that rotated fast; he had very nice periscope setup with 1x and 6x scopes hooked into the gun with strong linkage.  He also had a telescopic sight to work with and the gun was stabilized.  This was a vast improvement over the unmagnified reticle on the first production models.

The Lee used a unique setup; the 75mm gun was aimed with an M1 periscope, with an M21A1 periscope built into it. The 37mm was aimed with an M2 periscope with an M19A1 periscope built in. Both the 37 and 75 mounts were stabilized. The prototype M6 Sherman used its own unique sight built into the sight rotor on the top of the turret, this was only used on a small number of production Shermans tanks.

Let’s look at the various periscopes and telescopes the Sherman used through its long life.  Let’s start with a look at the various versions of the periscope sights the production Sherman and the TDs based on the chassis below.

 

The M3 Periscope Sight

Since I just have a little info on this from TM 9-731B on the early M4A2, don’t have much to put here. Maybe this periscope is the one I’ve read about getting foggy on the inside in cold or humid locales. It was quickly replaced with the M4 detailed below.  This was one of the non-magnified periscopes.

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The M4 Periscope sight

The Periscope M4; it had an M38 telescope with ballistic reticle inside, but no magnification. The M4 was not well liked, and the mount it fit in, was made from sheet metal and was a little flimsy.  The linkage that attacked it to the gun wasn’t very robust, and could be knocked out of alignment annoyingly easily.  On early Shermans this was a big complaint, since they did not have a direct telescope yet. You couldn’t really take advantage of the M3 75mm guns range with this sight setup either since it had no magnification. The later better periscopes like the M4, M4A1 and M8 series would all fit in the old mount though.

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The M4A1 Periscope Sight

Next came an improved version of the M4, the M4A1, and they came with an M38A2 telescope, this one was magnified, but not much at 1.44x, and a 9 degree field of view. Later versions of this periscope had illuminated reticles. The mount was not improved though nor was the linkage.  The M4A1 periscope was changed when the 105mm and 76mm armed Shermans came online, when used with these guns, they had the M47A2 for the 76 tanks, and M77C for the 105 tanks. Hunnicutt doesn’t specify if these were also 1.44X. This periscope was found on M4A1, A2, and A3 76 tanks during WWII.

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The M8/M8A1 Periscope Sight

The M4A1 periscopes were replaced by the M8 and M8A1 periscopes. They were a lager tougher improvement on the M4 series, and had the M39A2 telescopic reticle for use with the 76mm gun, since it had the same reticle as the M47A2 used in the M4A1 periscope.  The M39A2 had 1.8x magnification, and a 6 degree FOV.  Even though at this point this was no longer the primary sight, the Army kept improving it. But the mount and linkage still remained an issue.

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The M10 Periscope Sight

The Army came up with another new periscope sight system called the M10. They started issuing it late in the war around the same time wet tanks start appearing. This was a much improved periscope; it incorporated two telescopes with reticles, one 1.x, with a field of view of 42 degrees, ten minutes for engaging close targets. The second periscope had a 6x telescope with an 11 degree 20 minute field of view. This periscope could be used with the 76, 75, and 105mm guns when the right reticle was fitted. There was also an M16 periscope, pretty much the same as the m10, but with a reticle adjusting system.

M10C was specific to 75mm Shermans.

M10D was used on 76mm tanks, and 105 tanks.
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The Periscope mount

for these periscopes were improved greatly when the 76mm gun and 105 tanks arrived, and the mount was made from a beefy casting, and all the linkage was made much stronger will ball bearing in all the pivot points. These would have shown up on M4A1 75w, M4A3 75w, M4A3 105, M4 105, and M4A3 76w, M4A2 76w and M4A1 76w tanks.

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You can see the old style periscope mount in this shot.

This improved mount was also incorporated into most of the post war rebuild and overhauls. It is very easy to spot, by the heavy cast iron hood over the periscope hole.

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In this shot you can see the improved heavy duty gunners periscope mount, spikes optional.

The Telescopic sights.

The Shermans fire control system was improved further by the incorporation of a direct telescope mount to the M38A1 gun mount. This prompted the creation of the full length gun mantlet to protect the scope. When these were retrofitted into older tanks, sometimes they would weld on armor over the scope, leaving a half armored mantlet.

The later 76mm armed tanks had the M62 mount, and it had a telescopic sight mount from the start.

The direct scopes went through their own evolution, and this information is put together from the various TMs on the tanks and Hunnicutt’s Sherman, and is not complete. I will update this section as I get more info on the topic.

The M55 Telescope: The first! For the 75mm and 105

This telescope had 3x magnifications with 12 degree 19 minute FOV. This sight was also used on the early production 105 tanks and most 75mm Shermans.

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The M51: Also the First, but for the 76 M1A1

The same scope as above, with the same specs, but with the reticle for the 76mm guns, and that’s all. There were complaints about the optical quality on these scopes, since the clarity wasn’t optimal.

M70 Telescopic Sight

The M50 sights were replaced with the M70 Series sights, the same size and magnification. What set them apart was there superior optical quality. The Army went on to develop many different versions of this sight. It was a 3X scope with a 12 degree 19 minute FOV.

M70F Telescopic Sight

This was version used on M4A3 75W Shermans.

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M70G Telescopic Sight

This sight was used on M10 GMC tank destroyers.

M70P Telescopic Sight

This sight was used on some M36 CMCs tank destroyers.

M71D Telescopic Sight

This was a 5x with a 13 degree FOV version of the scope. It had the reticle for the 76mm guns and was used on those tanks. This was the sight commonly found on M4A1 and M4A2 76 tanks.

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M71G Telescopic Sight

This version of the M71 was issued with the Jumbo tanks.

M72D Telescopic Sight

This was used on the 105mm armed Shermans.

M76F/D Telescopic Sight

These telescopes were used on the M36 GMC tank destroyers.

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M76G Telescopic Sight

This scope only had a 3x magnification, with a 21 degree, 30 minutes FOV, and was used in 105 tank applications later in the war.

M83 Veritable Power Telescopic Sight.

This scope had two settings, 4x 7 degrees, 40 minutes and 8x 4 degrees, 15 minutes, and M83D version of this sight worked with the 76mm guns when in an M62 mount. I have not seen this one mentioned anywhere but Hunnicutt’s Sherman book. That doesn’t mean it didn’t get issued as a replacent later in the war, since I’m going off TM’s and spec sheets and those are a small snapshot into a tanks actual combat gear.

. . .

 

Indirect Fire Control Gear

You would think that would be it for fire control equipment, but it’s not, because all Shermans came equipped with the equipment for their tanks to work as impromptu artillery batteries all Sherman based TDs had this gear as well. The US Army had this extra gear installed all the way up to the M60 tanks. During the war, some tank and TD battalions were very good at being artillery; other units didn’t train for it, and were not good.  This was a good way of keeping tanks useful in Italy, and they filled this role a lot there. I do not think this was something many other nations did with their tanks.

Azimuth Indicator M19

The Azimuth Indicator was mounted near the gunner, right behind the traverse control. This device was used to dial in what direction the gun needed to be pointed in to carry out the fire mission.

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Gunners Quadrant M1

The Gunners quadrant is a portable precision instrument used for measuring the elevation or depression angles of guns and howitzers. It can also be used for checking the adjusting of elevation devices on sighting equipment furnished with a gun or howitzer. This was taken right from the Characteristics in tech manual 9-1527.

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Elevation Quadrant M9

The Elevation Quadrant M9 was used to lay the tanks main gun in elevation for indirect fire. There are detailed instructions for setting it up in TM 9-748.

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A Sherman unit trained in how to act as an artillery battery would probably be told they were on call when not in direct combat but close enough for the 75s to reach. They would have men manning radios in the tanks while other tasks were being done, like maintenance, personal things and eating. When they got the call, the designated battery commander for each platoon would listen to the directions on the arty net or get in direct contact with the spotter. In many cases they would wired into the directly, so they wouldn’t need to worry about radio reception. They would relay the aiming information out the tanks on the radio or phone net and then they would start firing.

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M4 being used as artillery

Once they started firing the hole crew would help feed the gun, and if they were doing it as a common thing they might even have large amounts of ammo unboxed outside the tank, where the driver and co-driver could feed them to the commander who then fed  them to the loader.  The M3 75mm gun worked well in this role, since the barrel had a life in excess of 4000 rounds.

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M4 105 acting as artillery.

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Sources: Sherman by R.P. Hunnicutt, TM9-731b, TM9-731G, TM9-748, TM9-748, TM9-750, TM9-752, TM9-754, TM9-759

#45 Gallery IV: You Guessed It, More High Res Photos!

Gallery IV: More photos, high resolution, with comments

More images, with captions, most high res, some sherman chassis based things as well.

Under_Sherman

A very early M4A1 Sherman, note the pair of M1919s mounted in the middle front of the hull, these were removed fairly quickly from production tanks. It seems to be hanging off a rather high drop off, and this gives us a great view of its belly. 
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A British M4A4 in Athens, during the Battle of Athens, in December of 1944, the tank is supporting the Scottish Parachute Battalion. It’s a later production tank with an M34A1 gun mount. 
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M4A3 76w Sherman with the 12th AD, in Husseren France. The tank is heavily loaded, and even the M2 is stored and covered. With all the mud around, you would think extended end connectors would be installed. 
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An M10 TD somewhere at the beginning of Operation Cobra,  the TD is somewhere in Normandy. Note the branches for camo. Look  at the communication wire running across the street. 
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French 2nd Armored Division M10 near Halloville France November 13th 1944. This looks like a mid production M10. That is some thick mud!
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M4A3 75w named Classy Peg passing a destroyed Japanese tank in Luzon, Philippines, January 17 1945.  These tanks were a terrible threat to the Japanese. 
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Clod hopper, an M4A3 or M4A2, on Iwo jima with the Marines, it was from C Company, 4th Marine Tank Battalion, and was taken out by a Japanese 47mm gun.  I wonder if the road wheels ended up on another tank. 
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A pair of composite hull M4 composite hulls burning. These tanks are US Army Shermans, and they are in the Guam, and I think they were taken out by a 47mm AT gun. The gun was probably behind were the picture was taken from. (Thanks to Russ Amott for help with the caption)
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An M4A1 76w passes through some kind of wall made of tree trunks. This tank has a split loaders hatch. Note the tree branch camo and how the gun is in the travel lock. 
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A Sherman V of the Canadian 29th Reconnaissance regiment(The South Alberta Regiment). The Tank was commanded by Major David Currie(VC), and the tank was named ‘Clanky’. This photo was taken in Normandy around Arromanches in July of 1944. A big Thank you to R.Wagner for the caption info.
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M4 105 serving with the French, tank names La Moskowa, the crew is hamming it up with a girl! 
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Riflemen of the 29th Marine Regiment ride a M4A3 Sherman 105mm of Company A, 6th Tank Battalion during the 6th Marine Division’s drive on Chuda along the west coast of Okinawa. It looks like the west coast of California!
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An M4A3 76w being given a ride across the Rhine River in a LCM, this seems like a precarious way to get a tank across, but maybe it wasn’t all the way loaded. 
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This one is a Marine M4A2 on Betio, Tarawa Atoll, and was named “Commando”(thanks to Russ Amott for the information on the photo caption) , for more information on this battle, see the new book Tanks in Hell by Gilbert and Cansiere.
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USMC PVC N.E. Carling in front of an M4A2 tank named Killer. It has a Type 94 TE KE tank on its back deck. Photo taken Kwajalein, Marshall Islands, 2 Feb 1944. Killer seems to have wooden planks added to the sides. 
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Later production small hatch M4 Sherman, probably somewhere in the MTO or ETO. This one seems to be captured and in use by the Nazis.
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This is an M4A3 76w tank, with the 784th Tank Battalion (colored) near the Rhine in early 45. 
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M4A3 76w Shermans from the 771st Tank Battalion supporting the 17th Airborne Division.  These tanks are sandbagged up, but not as extensively as some other units would go. 
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An M4A3 76w from an unknown unit passes by the corpses of Nazi troops. You can soo a wooden AT stick box and one of the deceased Germans seems to by laying on one.
Äâå ÁÐÝÌ ARV M31 (èç 3rd AD) âîçëå ïîäáèòîãî "Øåðìàíà". Saint-Fromond, Íîðìàíäèÿ, 14.07.1944ã.*
A M4 being recovered by a pair of  M31 Armored Recovery Vehicles near Saint Fromond France 1944. They are dragging it, since it looks like it has a lot of suspension damage. 
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An M4A3 76w HVSS from the 749th Tank battalion has collapsed a wooden Bridge, in Glossbliederstroff on the Saar, Germany

#41 Gallery I, Mixed High Res Sherman Photos, With Comments.

Gallery I, Mixed High Res Sherman Photos: Some With Comments.

 

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A nice color photo of an M4 stuck in Italy. It’s hard to tell if it is knocked out or just stuck, for the purposes of the fight it was in, there is no difference though.
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A burned out M4A3 76w in Neumarkt, Germany April of 1945.
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A knocked out M4A3 75W with concrete amor, in front of a M4A3 76w with similar armor, in the back also knocked out. This is arnoldsweiler Germany, tank unit unknown, the is from the 415 regiment of 104 Division.
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M4A3 75 from the 761st Tank Battalion supporting the 103rd ID near Nieffer France, this could be a small hatch M4A3 from the first batch Ford made, but its hard to tell from this angle.
747 Tank Battalion, Schleiden, 1945
A pair of up armored, with layers of steel track and sandbags, M4A3 76w Shermans, with the 747th Tank Battalion, Schleiden, 1945. All the added stuff would be be shedded just about as soon as the war ended.
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14th AD M4A3 76w column Hochfeld France 45
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A huge pile of rocks, with an M4A3 76W HVSS tank with add on Armor parked off to the side. The Easy 8 looks like its from the 4th AD, 37th Battalion. it looks like the rocks may be from fortifications German troops made.
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M4A3 with the 12th AD in Schneeberg Germany 1945, this tank has a threaded and capped M1A1C and a split loaders hatch.
9th Armored Division, Westhousen, Germany, 10 April 1945
M4A3 75w shermans with the 9th Armored Division, Westhousen, Germany, 10 April 1945, this picture is interesting, there’s a lot of garbage around the tanks, I wonder how many days they were there?
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A pair of 3rd AD M4A1 76w tanks in Schevenhutte 1944, parked in front of St Josef church on September 22, 1944, the wires hanging down are probably communication wires.
3rd Armored Division, Stolberg, 1944
M4 tank 3rd Armored Division, Stolberg, 14 october, 1944. The men on the tank are from the 36th infantry. This is when sandbagging started, as more and more encounters with german infantry with panzerfausts and panzerschreck began happening
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A pair of burnt out Canadian M4A2 Shermans of the 10th Armored Regiment (The Fort Garry Horse) at the foot of the church at Rots – June 1944 (Huge Image)

 

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3rd AD M4 in Stolberg 1945, if you look close there is a M3 Lee based M31 in the background.
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A nice photo of an Easy 8s, or M4A3 76w HVSS tank, and what looks like an M4A1 76w in the background.
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A nice photo of an 2nd Armored Division M4 coming off an LST on Utah Beach Normandy June 8th.
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A Badly damaged M4A3 76w tank that looks like it had a dozer blade. It’s from the 1st Armored Division in Italy 1944.
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An M4A1 in Italy on the Gothic line, town of Ponsacco, 1944, I wonder what this street looks like today.
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An M4 in Milan Italy in front of the Piazza Del Duomo
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An M4 showing its off road prowess
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An M4 doing it thang in some ruined town in Europe.I think the tank is with B Company 37th Tank Battalion, 4th AD. 
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A well camouflaged M4 is the subject of this beautiful high res photo.
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A nice high res photo of an M4 Composite driving down a street in Avranches, on August 4th, during operation Cobra.  The town is in ruins, but was an important because it was the gateway from into Brittany from Normandy, this tank is most likely with the 6th AD, (thinks to Russ Amott for more info on the photo)
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A small hatch M4 somewhere in Europe
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A nice high res photo of an M4A4 probably about to be shipped to England, or just arrived there. Notice the ‘Comb’ device on the front differential cover, it has a wire going from it to through the bow gun mount to the tanks brake levers, so the brakes could be released without breaking the extensive weatherproof packing they have done. Look at all that duct tape!!
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A nice high res photo of a M4A1 with a strange rocket launcher setup.
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A nice color shot of an M4A1
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A nice high res photo of an M4A2 76 wet, a pretty late production one, much like the one fished out of the ocean in the sunken Shermans post.
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I high res pic of what looks like a couple of platoons of small hatch M4 and M4A1s parked on a street somewhere in Europe.
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A very nice high res pic of an M4 being used as an artillery piece, near Vicht Germany 17 November. Unit unknown. The M4 was named ‘Ink spot’
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Marine M4A2 on Peleliu, I think.
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Shermans at rest in a pretty flower field in Italy.

# 15 Turrets: They Are The Combat Power Of The Tank

 

Turrets: They Rotate, and have Guns

Cute puppies!
Marine Cleaning his Tommy gun on a Late model M4A3 75 Sherman. Note the all around vision cupola with periscopes mounded in the center of the hatch.

The Sherman had two turret types the 75mm turret, and the later T23 turret with the M1 series of 76mm guns. The Jumbo had an up armored version of the T23 turret.

split hatch details

One of the things that really set the Sherman apart from its piers, and gave it very good longevity, was the size of the turret ring. The Shermans was 69 inches, positively huge for when it was designed, the early T-34 had a 56 inch ring, and the later version with 85mm gun had a 63 inch turret ring. Nazi Germans are not very good in this area, PIII having a 60 inch ring, PIV having only 63 inches, and the Panther only having a 65 inch ring. Even the Tiger wasn’t huge, at only 70 inches! So what makes the size of the ring important? It is one of several factors that determine the maximum size gun you can mount on the tank. The other factors are the mechanical reliability of the vehicle and its load capacity, and how good the country building the tank was at making recoil absorption systems for the guns. The combination of automotive reliability, load capacity, turret ring diameter, and turret size allowed the Sherman to be up gunned for decades. These factors were far more important than armor thickness when it came to the Shermans longevity. That the Sherman received more powerful guns than the Panther had, or could have had, is just one more reason why the Sherman was such a great tank, and better than the Panther.

turret collector ring
The turret collector ring allowed the turret wiring to go into the hull and still allow 360 degree traverse and not tangle any wires. All Shermans had essentially the same one.

Now let’s talk about turret drive motors.  There were three types on 75mm Shermans.

Oilgear: All models of Sherman tank had both powered and manual turret traverse. They did try various brands and types though. The preferred on the early Shermans was the hydraulic mechanism made by Oilgear Company. The Oilgear unit was both more precise because it had veritable sensitivity, and more robust since it was able to keep the turret spinning even with minor flaws in the race or ring gear, than the other choices. Oilgear could not keep up with all the factories producing Shermans, so they had to go to other companies.

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The Oilgear traverse system and gunners station in an M4A2 76 HVSS tank
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The Oilgear Traverse System, and foot pedal triggers, and elevation wheel in a restored M4A2 76w HVSS tank

The Oilgear unit was hydraulic, but powered by its own electric motor that spun a hydraulic pump and turbine setup to rotate the turret. The whole assembly was small enough to be mounted to the side of the turret, with a fair amount of room for the gunner.

Logansport: This Turret drive was very similar to the Oilgear unit, just not as precise, nor as good at dealing with imperfections in the turret race or ring. This unit was so similar the electric motor powering the hydraulic pump and turbine used the same reduction gears as the Oilgear unit.

The Logansport unit used the same mounting bracket as the Oilgear unit as well. The sensitivity to problems with the tolerances on the turret ring would make this drive more likely to fail from minor damage that the Oilgear unit would shrug off.

Westinghouse: The Westinghouse unit was just a big electric motor hooked to reduction gears. Since the motor ran at a faster speed, it had to be adapted to the stabilizer system, but was still able to fit the same space and use all the mounting brackets of the other systems.

M4A4 Armament diagram westinghouse traverse 75mm early turret
Westinghouse traverse controls

The Westinghouse unit had the same problem with minor flaws in the race or sensitive to tightness in the ring gear.

Now, this would be a quality assurance problem at the factory in most cases. IE, when the tank got to the end of the line, and the QA inspector rotated the turret, and it screeched and slowed down over 10 degrees of rotation, it would be rejected, and sent to the factory’s QA shop to be fixed.  Battle damage might have caused some problems as well, but if the tank took enough of a hit to damage the teeth on the ring, or gear, it was probably going to be knocked out, and in really bad shape. That speculation based on how well many turret rings held up after years on firing ranges, when the wreck they were in was restored into a beautiful working tank.

On the later T23 turrets, the Oilgear system was used for traverse control and an improved Westinghouse stabilizer was used as well.

The Westinghouse stabilizer: All models of the Sherman but the 105 armed tanks had a stabilizer to control the main guns in elevation while on the move. It used a gyroscope and hydraulic power pulled from the turret drive system to keep the gun steady in the vertical while on the movie. The system is often disregarded as an advantage by detractors, for a few reasons, but none are valid in a technical sense. The stabilizer was a very advanced piece of kit, and something the Germans could not copy, and never installed a similar system on a wartime tank. That it was complicated and the crews lacked training in using it, doesn’t mean it didn’t work and offer advantages to crews who bothered with it.

The original stabilizer was a little complicated to setup properly, since many armor units received their tanks and maybe some manuals for them, when they formed, they often did not have a single man in their company who really knew how to make the stabilizer really work. This lead to it being turned off by a lot of early war crews. The wrongheaded belief the equipment was useless followed that. The Army did a test on it and found the stabilizer, when setup, and used by a crew who knew how to use it, it helped a great deal in getting off a fast first shot, when the tank came to stop to shoot.  If the tank rocked, the gun stayed more or less on target. This was a big advantage to getting that all important first shot/hit in combat.

The Westinghouse stabilizer was improved and simplified in the second generation Shermans, the large hatch 75 and 76 tanks would have gotten it.  It was easier to setup and maintain, and the Army worked on getting crews trained on it.

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M3 2 inch Mortar

The M3 2 inch Smoke Mortar:  The M3, 2 inch smoke mortar was installed in the turret, with the muzzle opening on the foreword left of the turret, on both the 75mm and 76mm gun turrets.  It was added to the tank at the request of the British, and was loaded and fired by the loader. The mortar was loaded from inside, but protruded into the loaders space, and was not well liked. It could only be aimed by rotating the turret, and not all late model 75mm and 76mm turrets got them. Post war, most were removed and the hole welded over.

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An M4 Composite hull, probably in the Philippines, with a good shot of the late model split commanders hatch

The Hatches:  The Sherman’s turret started off with a single large split commander’s hatch. This hatch incorporated the m2 .50 HMG mount and rotated. It also had a standard periscope mounted in one side of the split hatches. This hatch went through several changes through its long life. Initially the split commander hatch just depended on the weight of the armored hatch cover halves to hold them in the 45 degree angel position that sat in when open. They could be knocked loose when the tank was moving over rough terrain, and really hurt the commander.  They added a pair of hatch locks at the factory, and fixed them in the field with kits. The final version of the split hatch had internal springs in the hinges to hold them open. There was also a version with a defect that passed factory inspection that showed up on some M4A1 76W tanks, where the split loaders hatch, essentially the same hatch that had been the commanders hatch, was used for the loader, .50 M2 mount and all.  This was fixed pretty quick though, and then the hatch was replaced by a the oval loaders hatch.

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In this massive image of an M4A1 76w tank, that has been modified with a flame thrower, after being repaired, note it has the split loaders hatch with the flaw that won’t let them open all the way.

When the second generation Shermans with the T23 turrets went into production, they all got much improved all around vision cupolas. There must have been a shortage of contractors who could make it, because it was in short enough supply, the second gen large hatch, M4A2 75s, M4 Composite hulls, and M4 (105) tanks were all built with the original split commanders hatch.  The all around vision cupola production were reserved for tanks armed with the M1A1 gun.  The cupola offered very good all around vision, with six armored glass viewing blocks, that were all replaceable, and a larger periscope mounted in a rotating center section of the hatch door. Towards the end of the war the new cupola became more available and was fitted to some of the ultimate production M4A1 75, M4A3 75w tanks, and M4A3 (105) tanks.

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in this nice photo of a early production M4A1 76w Tank with the split loaders hatch. It’s also a pretty good shot of the all around vision cupola

The oval Loaders hatch: The version of this hatch on 75mm turrets looked the same but was slightly smaller than the one used on the T23 turrets. The hatch was a spring loaded oval hatch, either just big enough to get though or, big enough to get through comfortably, in the T23 versions. On the T23 turrets, when the oval hatch was installed, a new fully rotating periscope foreword of the hatch replaced the one that was mounted in the old split hatch.

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Soviet M4A2 76W tanks with oval loaders hatches.
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A late production M4A2 75 with a large hatch hull, oval loader’s hatch, on what is probably a high bustle turret, with a split commanders hatch.

. . .

Now for a final bit of information on the turrets and the stuff mounted on them. Over time the turrets picked up an external vane sight the commander could use to roughly put the gunner on a target, it looked like a whale fin in front of the commanders hatch on older 75mm Shermans. This was refined into a more useful, and less odd looking site that could be used from inside or out of the turret.  The .50 caliber machine gun mount started on the commanders hatch, eventually moved to the loaders hatch, and then to the middle between the two hatches.  There was also a spotlight mount added, and it ended up being on late 75mm turrets, the T23 76mm turrets, and even retrofitted to older 75mm Shermans.  The mount had an armored plug, the spotlight plugged into, and then could be controlled from inside the tank, much like the spotlights you see mounted to the side of police cars. The turrets also started out with no brackets for storing the heavy machine gun, but they started showing up on 75mm turrets and were on almost all T23 turrets.  Even where the lifting eyes were moved around on the turrets.

 

From looking at period pictures, it was very common for the gunner or loader to ride standing in the commanders hatch, while he was in it as well, the split hatch cupolas were that big. I thought I wouldn’t see the practice on tanks with the all-around vision cupola, but I found a few were the crews did it there too.

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This Marine M4A1 in the jungles of Cape Gloucester has it’s commanders hatch being shared by two crewmen

 

Riflemen of the 29th Marine Regiment ride a M4A3 Sherman 105mm of Company A, 6th Tank Battalion during the 6th Marine Division's drive on Chuda along the west coast of Okinawa. After expecting a contested landing on April 1, 1945, and seeing little of the Japanese, the Americans were in high spirits as objectives are taken ahead of schedule in Northern Okinawa; the Shuri Line would rob them of their high morale. The 29th Marines cut off the Motobu Peninsula and seized Chuda at 1200 Hours on April 6, 1945. Tank-infantry teams encountered sporadic resistance during the initial invasion; most problems were from the Japanese blowing bridges as they retreated inland. Destruction of bridges had been inept; frequently only a span of the bridge had been blown or cracked. The engineers cut quick bypasses for the vehicles, repairing the broken spans later. 500 M4A3 Shermans with the M4 105mm gun were built in late 1944. Later versions of the 105mm Sherman had a more advanced horizontal volute spring suspension (HVSS) with wider tracks that allowed for a smoother ride. Note partially dismantled deep wading gear to allow the M4A3 to move through deep water during the landings a few days before. The M4A3 Sherman with the M4 105mm howitzer was not popular with the tankers, who preferred the M1 76mm high-velocity gun in case of tank-against-tank engagements. However, the 105mm-equipped Shermans were very popular with ground troops, who used tanks as mobile pillboxes, taking out Japanese positions with point-blank high explosive fire.
On this M4A3 105 in Marine Service, you can clearly see the commander and probably gunner sharing the all around vision cupola!
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An Army M4A3 75 tank with a split commanders hatch, oval loaders hatch, and the commander and gunner sharing the split commanders hatch, somewhere in the Philippines.

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An M4A4 that has been modified to take a different motor, with a mid production 75mm turret, with split commanders hatch, and a welded up pistol port. It also has the stubby mantlet, and you can just make out the original commanders vain sight in front of his hatch

 

The standard 75mm Turret:  The Sherman’s First Turret, It Had Many Minor Changes

The standard 75mm turret started out with a stubby rotor shield that just covered the base of the 75mm gun. These early turrets didn’t have a direct telescopic sight for the gunner either. The gunner had to rely on the M4 periscope to aim the gun. The turret had one large hatch for the whole turret crew to get in and out from and a pistol port on the loaders side that could be propped open and spent 75mm shells dumped out.  The loader and commander had fully rotating periscopes to view the world through, the commander’s periscope was in his hatch, the loaders right above his station, and the middle of the turret roof had an armored ventilator. Many of these turrets had a weak spot in the armor due to an area machined to fit the turret drive. This area was covered with additional armor on once the problem was discovered.

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In this shot of a Sherman wrecking yard in Europe, you can see the early 75mm turret with depot or even factory level rebuilds, on these tanks before they were knocked out. They could be M4s, or M4A3 tanks that were used in the US for training and refurbished on shipped to the ETO. You can see the split commanders hatch, though missing the hatch doors on two of them, the full length gun mantlet, the welded on cheek armor over the weak spot and the commanders old style vane site.

The small rotor shield and lack of telescopic sight were some of the first production line changes, and older tanks were field modified with kits to update them, often only covering half the turret with added armor on the mantlet to protect the new telescopic site. The new factory full size rotor shield covered the majority of the turret face with much thicker armor. The next big change was a weak spot in the right side of the casting where a thin spot was made while machining the turret for the gun mount was discovered, and armor was welded on the outside of the turret to thicken it back up. Tanks were retrofitted with this armor in the field, and later the casting was changed to include the thicker armor over the area, eliminating the need for the welded on cheek armor.

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This M4 Composite hull tank in the Philippines has the split style commanders hatch on a 75mm turret with most updates

At some point while all the above was going on someone decided the pistol port was a weak spot and it had to go. So they started welding them closed at the factory, and then the casting had them removed. Then the men in the field went ape poop, and they put it back in, around the time the ultimate 75mm turret went into production, with the thicker armor cast in, the pistol port back, a new all-around vision cupola for the commander and an oval hatch for the gunner.  This would be the final configuration of the 75mm turret. The tolerances used by US tank factories were close enough turrets cast at one factory could be used at another with no modifications. Many older surplus turrets left over from the tank retriever conversion program were used in later production, with all the updates added, and a hatch cut in for the loader. Due to a shortage of all around vision cupolas, many 75mm turrets with a loaders hatch ended up with the old split style commander’s hatch.

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This M4 has a split commanders hatch, commanders vane sight, full gun mantlet, and welded up pistol port

When hull production switched over to the 47 degree frontal armor configuration, and they went with the large driver and loaders hatches on the M4, M4A2 and M4A3 production, the 75mm turrets needed modification. The hinge for the larger drivers and co  drivers hatches stuck up higher than the older small hatch hulls, they could interfere with the turrets rotation, since they barely cleared the bustle were the radio was mounted in the back of the turret. The first solution was to notch the bustle a little, but they also changed the turret casting, raising the whole bustle area and making the top of the turret flatter.

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Chopper is a M4A3 75 W tank, used by the Marines on Okinowa

The turret drive motor was either an electric motor driven hydraulic system or a strait electric motor driven system. The hydraulic system was the preferred, but when that system was in short supply the electric system was substituted.  The 75mm turret could rotate 360 degrees in 15 seconds with the power traverse. It had a manual traverse system as well, and elevation was handled through a manual wheel.

For the very best in minute detail on this subject, please check out the Sherman Minutia site. One minor bit of trivia about the original style turret, the D50878, and D78461 castings, the ones produced for the 105 armed tanks were unique, in that they had an extra armored ventilator whole drilled in so another one could be mounted. So the 105mm turrets really are 105mm only. I’m still not sure if there is a 1/35mm Sherman M4 105, or M4A3 105 with the correct turret.

 

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An early T23 turret on an M4A1 76w tank. Not all around vision cupola for the commander and the split loaders hatch

The T23 Turret: Developed For the Failed T23 program, It Found a New Purpose on The Sherman

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The origin of the T23 turret, the fascinating T23 medium tank. It used an gas generator powered electric drive system, but unlike the ones the Germans used on the Elephant, it worked.

While the 75mm turret was still in production and being improved, the T23 turret, taken from the failed T23 medium tank project, went onto the Sherman with the M1A1 gun on the big hatch, wet ammo rack hulls. This turret was larger and could fit the 76mm gun with much more comfort than the basic 75mm turret. All T23 turrets had loaders hatches, though early production T23 turrets used the hatch that had been the commanders hatch on older Shermans for the loaders hatch and used the new all-around vision cupola for the commander. This didn’t last long; it was found the narrow area between the two large hatches on the roof was a weak spot. The big loaders hatch went away and an oval hatch went in.  These turrets had the same traverse speed as the 75mm turret and the same ROF.

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Pn this M4A1 76w tank you can see the commander in the all around vision cupola, and the split loaders hatch open

The T23 turret came in around 4000 pounds heavier than the 75mm turret. The automotive systems of the Sherman tank were strong enough to support the extra weight without any real change in performance or longevity. The drivetrain didn’t receive any changes at all as far as I can tell, and only the Jumbo tanks got a different gear ratio in the differential. All the extra weight in sandbags, concrete and real armor did shorten the life of the automotive components but not by a significant amount.

All T23 turreted 76mm gun tanks, had wet ammunition storage, as did the Jumbo tanks, but not all large hatch hulls did. The M4 (105), M4 composites, and M4A2 large hatch 75mm tanks all had dry ammo racks.  The T23 Turret would get the smoke mortar, and an extra periscope hole machined in when the split loaders hatch was replaced with the oval hatch.

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T23 turret on an M4A3 with the 14th AD
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Another M4A3 76 tank with T23 turret serving with the 14th AD

Sources: Armored Thunderbolt by Zaloga,  Sherman by Hunnicutt, Ballistics and Gunnery by Bird and Livingston, The Sherman Minutia Site, Son of a Sherman by Stansell and Laughlin, M4 Sherman tank at war by Green, Tanks are a Might Fine Thing by Stout, the Lone Sentry, TM9-731B M4A2, TM9-731G M10A1, TM9-745 GMC M36B2, TM9-748 GMC M36B1, TM9-750M3, TM9-752 M4A3, TM9-754 M4A4, TM9-759 M4A3,  FM17-12 Tank Gunnery, FM17-15 Combat Practice firing, FM17-67 Crew Drill and Service of the Piece M4 Series

#14 Main Guns: Things That Go Boom, Some Bigger than Others, but None Bad

Main Guns: The Sherman Mounted Six Different Guns, But Not On All Versions, NOW WITH GUN DATA SHEETS!

The Sherman tank and its chassis was host to a variety of guns.  Most had the M3 75mm gun, or the M1A1 76mm gun, but many were also equipped with the British 17 pounder, the M3 90mm, 3 inch AT gun and the M2/M4 105mm howitzer.  I will cover each below.

The M3 75mm gun: When it first saw Combat, it was a Great Tank Gun

The M3 75mm gun was a great tank gun for the time the Sherman was first introduced to combat, and was based on a well-liked WWI French field gun. When it first saw combat it could punch through any German tank it faced, from just about any angle. It’s a myth the Sherman was designed to only support infantry, though it’s primary role was not anti-armor, it was still designed to face other tanks.  The gun worked well in the infantry support role as well, with an effective HE and WP smoke round, and a canister round. This gun had a very high rate of fire in the Sherman (20rpm) and was mated with a basic stabilization system. This system did not allow shooting on the move accurately, but did allow the sights and gun to be put on the target faster when the tank came to a stop to shoot. No world war two tanks could shoot on the move with a real chance to hit even a stationary tank sized target. With a twenty round a minute rate of fire, the Sherman could pump out a lot of HE in support of the infantry, and it was not unheard of for the tanks to be used as artillery. The Sherman tank was equipped with all the gear to act as artillery if needed and was a regular occurrence in the MTO, less so in the ETO.

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M4A2 75

Sherman tanks with the 75mm gun carried between 104 and 97 rounds of main gun ammo. Only 10 to 15% of this ammo was AP, that’s how rare other armor was, HE would make up the majority of the rest of the load, with maybe another 10 to 15% being WP smoke, since this was also a somewhat destructive shell, because it caused fires and WP when it landed on a person was hard to put out. There was also a canister shell, but I think it was only used in the PTO.  The rate of fire on the gun is a little misleading, since depending on the Sherman, you would have between 6 and 12 ready rounds, more on the very early Shermans with ready rounds around the base of the turret basket.  Once the ready rounds were fired, and often, the ready rounds are kept in reserve anyway, to deal with unexpected threats.  Wet Shermans had an armored 6 round ready box mounted in the turret, the rest of the ammo was in armored boxes under the floor. Most wet tanks had a half turret basket or none at all. This was a problem common on pretty much all tanks.

m4a3 75 m70f reticle

The M3 75mm gun was so well liked, the British essentially ended up converting many of the QF 6 pounders to fire the same round, fired with basically the same ballistics, with the advantage of not needing to modify the current tanks mount.  The WF 6 pounder was a better AT gun, but, it’s HE round was not very good. The M48 HE round used by the m3 75mm had 1.5 pounds of TNT inside, and since the Sherman could fire them fast, and the shell was fairly handy, it’s easy to see why the gun was good at infantry support.  It really only lacked the ability to pen the frontal armor of the German Tiger and Panther, but those tanks were rare enough, or easy enough to get side shots on, the 75 did the job, and did it the whole war, since the 76mm armed Shermans never totaled more than 53% of the Sherman force in Europe. The M3 75mm gets a lot of flak thrown at it by ignorant people who think it was a low velocity gun that could not penetrate armor. These people must be confusing it with the German KwK 37 L/24 75mm gun that armed the first versions of the Panzer IV.

 

75mm M3 spec booklet MK VI Download. 

 

The M1/M1A1/M1A2 76mm gun: Made by Oldsmobile, It was Not a Great Gun, but Did the Job

The M1 series of 76 mm guns went into production before the US Army had any idea of German heavy tanks, or the Panther. They were just looking ahead, to keep the Sherman as good a combat weapon as possible, and to stay ahead in the arms race.  They had the 3 inch AT gun on hand, and had used it in the M6 and M10, but it was really to bulky to work in a medium tank turret.  The Army decided to design a gun with the same ballistics, but in a much lighter, and less bulky package, in doing so the M1 gun was born.  The gun overhung the front of the Sherman a lot so the Army decided to shorten it over a foot. It still seemed to match the ballistics of the 3 inch AT gun though; guns with the shorter barrel were designated M1A1 guns.  The first three hundred of so guns produced by Oldsmobile lacked muzzle brakes or the threads to install them. Gun’s produced after that had the threads and a protective cap over them so a brake could be installed later. The final variant of the gun was the M1A2, installed in late production 76mm Shermans, this gun always had the muzzle brake, but had a slightly different barrel, with a minor change to the rifling twist.

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M4A1 76W with unthreaded M1A1 gun

Much of the later large hatch hull tanks were produced with a larger turret to accommodate the M1 family of 76mm guns. This turret came on M4A1s, M4A2s and M4A3 tanks.  The M1A1 on the early tanks, like the M4A1 76 w tanks used in Operation Cobra, came without muzzle brakes. When firing during dusty -conditions the view of the target would be obscured by dust stirred up from the guns blast, the fix for this was for the commander or another crewman to stand away from the tank and talk to the crew over the intercom, via a long wire, and correct the shots onto target. Not a great fix…The final fix was muzzle brakes; it took a little while for supply to catch up with demand but they were showing up on Shermans in Europe by late 44, and by March they seemed to be in stock, and showing up on tanks that had the protective cap before.

Another problem was the gun was not a huge improvement over the M3 75mm as a tank killer, and was not as good as an HE thrower. As mentioned before, several tank divisions didn’t want the improved Shermans at first. The penetration problem would be partially solved with HVAP ammunition, but by the time it was common, German tanks to use it on were not.   Post war, ammunition would be further improved and there would be no shortage of HVAP ammo in Korea, so the US Army would soldier on with the gun, in its final improved form, the M1A2.

The M1 series of guns were also stabilized when installed in the Sherman, but it was the same system used with the 75mm gun, offering limited advantages. The Nazi Germans never fielded a stabilization system of any kind on their tanks. Tanks with the M1, and M1A1 guns carried 71 main gun rounds in wet storage racks in the floor, with an armored 6 round ready rack on the turret floor.

M1-M1A1-M1A2 guns 76.2mm Sherman Tank Gun PDF file.

The M3 90mm Gun: The Most Powerful AT Gun the US used During the War.

The US M3 90mm tank gun started out life as an AA gun, a very good AA gun, unlike the very overrated Flak 18/36/37.  As the AA gun was developed, it’s mount gained the ability to be used against ground targets, with up to -10 degrees depression.  The ballistic performance on the gun was good, but what really made the AA gun shine was the AA gun system that incorporated Radar, and proximity fuses, sci-fi tech to the Germans, but pretty typical American technology for the time, it was the best land based AA gun system of the war.  Contrary to some claims, it was pretty rare for US 90mm AA guns to be used in the direct fire role. The US Army was rarely desperate enough to have to resort to such tactics.

American soldiers of Patton's Third Army standing in front of their M36 TD while rolling up a Nazi flag they have taken as a trophy after the capture of Bitberg.
M36 with M3 90mm

When the US Army started looking into a bigger AT gun than the 3 inch, the M1/M2 90mm AA gun was a natural choice.  The tank mounted weapon would be designated the M3, and with a barrel threaded for a muzzle brake, the M3A1. When tested against the British 17 pounder gun, the M3 had slightly inferior performance, but was more accurate. The US Army preferred the 90mm over the 17 pounder for various reasons, the biggest being it didn’t have scary flashback out of the breach on firing, making it seem like a somewhat shoddy design. The 90mm M3 would soldier on the in the M26/46 tanks,  but would be replaced by improved 90mm guns on the M47 and M48.

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As a dual purpose tank gun, the M3 90mm was good. It’s rounds were not to big for one man to handle. It had good AT performance, and a more potent HE round than the M3 75mm gun. When installed on the M36 Tank Destroyer, it was able to deal with the rare heavily armored German threat, if the regular Shermans hadn’t already killed it by the time the M36 got there. Since the gun was not overly hot, it didn’t wear barrels out fast, so it could still be used in artillery role.  

M3 90mm gun data on PDF

The 3 Inch AT gun: An Old AA Gun Finds a New Use

The 3inch AT gun started out life as a AA gun. It was still being used as one for the first half of the war.  It was a natural choice as an AT gun since it was being replaced by the M1/2/3 90mm AA gun system. The gun was large, heavy and bulky, and the M10 tank destroyers turret had to be rather large to fit it.  They were also able to fit it in the T1/M6 Heavy tank, but it was clear it needed a redesign to fit in a smaller turret like the regular Sherman. This ultimately lead to the M1A1 gun discussed above.

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M10 with three inch gun

There was also a towed AT gun version of this weapon, it was generally not well liked. It was too big to move around easily by hand, hard to hide, and didn’t have great pen to work well as a fixed gun. At one point in the war, nearly half the Tank Destroyer Battalions were towed, and equipped only with the towed guns and trucks to move them. These TD battalions had little luck, and some really got clobbered in the Battle of the bulge.

Ultimately this guns use was more about taking unused guns on hand and getting a decent AT weapon out the door fast, by using them for this new purpose. They were not perfect, and as towed weapons, even really good, but on a mobile platform like the M10 or even the M6 heavy tank they did the job well enough.

3 inch M7 Gun spec sheet PDF download

The M2/M4 105mm Howitzer: Artillery in a Sherman Package

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M4A3 105 HVSS tank

The US 105mm M2/M4 howitzer was the biggest gun installed in the Sherman, the versions of the Sherman with this gun were developed to replace the M7 Priest, but never fully did so during WWII.  They were used in the same role, or in limited direct support roles. These tanks did not have a stabilized gun or wet ammo racks, but did have the large hatch hull. All 105 Sherman tanks, either M4 (105)s or M4A3 (105)s were produced exclusively by Chrysler. 105 tanks carried 66 rounds of main gun ammo, in dry ammo racks.

Sherman tanks equipped with the 105 often found themselves pooled with the others from the three companies of a battalion, with the two from the battalion HQ, so the Tank Battalion could have their own mini 105 battery on call. When working with their assigned company, they were often held in the back, and supported the gun tank platoons with indirect or direct fire. Use in direct fire support would be the rarest use for them, but it did take place.

The 17 pounder gun: 76.2mm of British High Velocity Boom Boom

The 17 pounder was developed to replace the 6 pounder, it was clear the 57mm 6 pounder wasn’t going to be able to handle tanks with thicker armor, but it stayed surprisingly relevant late into the war.  The 17 pounder started development in the final months of 1940 and was going into prototype testing in late 1941.  The first few AT guns were made by slapping the gun onto the 25 pounder carriage called the 17/25 pounder, and some were shipped to North Africa, to counter the supposed Tiger threat. The full production QF 17 pounder AT gun was available by the Italian Campaign.

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American Test Firefly with 17 pounder

The main reason the gun was a better AT gun than the US M1A1 gun was the round had a lot more propellant behind the projectile and then the Brits came up with the super velocity discarding sabot round. This new round had very good penetration, but had some serious accuracy problems.  The accuracy problems with the SVDS ammo were not fully solved until after the war.  The gun was intended for tank use, but the British Tanks meant for it had to many developmental problems, and were not going to be ready by Normandy landings, so the Sherman Firefly was born. See its own section for more info on these Shermans.

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M4A1 with 76 gun

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M4 105

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What’s left of an M4A3 75w on Iwo Jima

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M36 with M3 90

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Sources: Armored Thunderbolt by Zaloga, Sherman by Hunnicutt, Combat Lessons,  Archive Awareness,  WWII Armor, Ballistics and Gunnery by Bird and Livingston,  TM9-374 90mm Gun M3