Category Archives: Ammo Storage

Post #70: Report on the New Weapons Board

Post #70: Report on the New Weapons Board

I downloaded this PDF, Report on The New Weapons Board 1944,  someplace, but since I don’t remember where I hosted it too.  The report documents the feedback the troops gave to the board on the various weapons they demonstrated.

The report was put together in early 44 to document feedback from the troops on current weapons, and proposed improvements, and replacements. There is a good amount of information on the M4 medium tank, and US Armor in general. Most of the combat feedback comes from the fighting in Italy, and North Africa.

The report also sheds an interesting light and gives evidence for the view that the US Army didn’t consider the improved early Sherman bad, and only wanted it replaced with something much better.  It also gives some interesting insight into the Shermans and what condition they were in when they got to the using units.

Feedback on current equipment and changes.

This is a typical M4 Sherman in Italy, the battalion is being used as an artillery battery, and this is an early production M4 with the M34 gun mount and it probably has a three-piece differential as well. It may even have DV ports. These tanks were common in the MTO even into 1944.

The first thing is this to note about the Sherman is the first mention of it is praise for the current models. This quote stands out, “No new type is desired unless the improvement in military characteristics is sufficient to warrant the changes and defects in the present standard tanks are avoided.” 

Another early model M4 in Italy, cheek armor, M34 gun mount, and an early 3 piece differential.

They did have a list of improvements they did want either done to the Sherman and to make sure the follow-on model, the T20 series incorporated them. 

  1. They wanted a 76mm gun like the 3-inch gun on the M10.  The news of the 76mm M1 series and the new Shermans mounting the gun interested the troops a lot. They brought an M4E6 76mm Sherman to show to the troops.
  2. Improved suspension and tracks. It turns out the rubber block tracks with no chevron were not well liked and wore out very quick in rocky, hilly terrain. The steel chevron blocks with rubber backs were well like and lasted much longer. This feedback is mostly from the MTO, the mountainous and rocky landscape was hard on tanks and even the Sherman had some issues. The complaints about the suspension had more to do with width than durability.
  3.   They wanted armored air cleaners on the M4 and M4A1 tanks.  It turns out the Air cleaners mounted under the overhang on the rear hull of the M4 and M4A1 tanks were prone to damage, and this damage was not expected and didn’t pick up until Italy so there was a shortage. All other models had the air cleaners inside the hull. Some units added improvised armor and some were added later in the production runs.
  4. Better ballistic angle around the front of the transmission housing.  The old three-part differential is what they are talking about. Most early Shermans had this type, and the armor was thinner than the later cast single piece units. There were two cast versions, an early thinner, but still no worse than the three-piece unit, and a later improved thicker one. There was a demand for add-on armor over this area, but it was never approved.
  5.  More power. Yet, when the M4A3 Ford GAA powered Shermans came online, they did not want to swap them in as replacements, and only wanted whole units who trained on them stateside first to be issued the improved tanks.  The M4A4 and M4A2 were not big enough improvements to switch to those motors. 
  6. Diesel engine. The US Army rejected the GM 6046, claiming it was not as reliable as the R975, but all the nations that did use this motor liked it.
  7.  They wanted better sights and fire control equipment. Many tanks in the MTO and NATO(North African Theater of Operation) had not gotten the M34A1 gun mounts with telescopic sights. The mount for the periscope sight had not seen major improvements, though there were field mods to make it work. The using arm was enthusiastic about the changes in the second gen Shermans fire control, but wanted even more advanced features, like rangefinders, and improved telescopes, since the current ones shot loose too!

There is also other tank related info.

  • The M3 75mm Gun –  Though well-liked for infantry support and deemed to be reliable and durable, the using arms almost universally felt the German 75mm PAK 40 guns were much better anti-tank weapons, and a high-velocity 76mm gun was in demand.
  • 75mm ammunition – these fixed rounds came unfixed, sometimes even in their travel packaging.  They wanted this fixed. They wanted the WP shells ballistics to match the ballistics of the common HE shell.
  • Large caliber cartridge cases – Steel cases for the 75mm rounds for the M3 gun were well received and proved more durable.  This was not the case for 105mm howitzer rounds.
  • 105mm howitzer armed tanks – This was not a popular notion because the M7 105mm GMC was inaccurate when used for direct fire to support infantry assaults.  The new weapons board did not agree, and plans for this vehicle were already in motion, and it would be well liked once issued.
  • Tank Officers – they wanted a tanker officer in the high-level headquarters to advise Division and higher level officers the best way to use tanks. AA and Tank destroyer officers were already an accepted part of these HQ staffs.
  • the 17-pdr gun – There was more interest in using this gun in M10s since the install was much simpler, the Sherman install was complicated and cramped and the Army was leary.
  • Tank Tracks – They show up again and the plain rubber block tracks could wear out in 250 miles in rocky terrain and lacked good off-road traction, and the using arm felt they were only good for training on roads.  The T54E1 steel chevron type was preferred and much more durable, but the T48 rubber chevron would work in the MTO but wore out faster than steel types. The T49 bar cleat was also not good on sidehill terrain. The using arm wanted a wider center guided track in the MTO because the side guided tracks on the Sherman were prone to throwing on irregular and rocky side slopes. Extended end connectors were well received by the using arms.
  • Tank Suspension – Sherman suspension was found to be durable, with few volute springs failing. The biggest problem was the bogie wheels since the rubber tires had an erratic failure rate, and unlike the spring failures, usually sidelined the tank.
  • Ammunition stowage – They using arms were not interested in changes that reduced the number of ready rounds. The turret ready racks were very popular and crews did not like their removal with the ‘quick fix’ mods. They were willing to risk the higher fire chance, for the faster rate of fire the early storage setup allowed. The crews did not get their way on this one, at least until the M26 went into production.
  • The Radios – They wanted a better radio in the M32 recovery vehicles and better, more comfortable headphones for the armor crews.
  • The M10 GMC – This TD was very popular, and received high praise all around. The using arm did not require a replacement, just improved M10s. ♠ One thing to note, most M10 GMCs in MTO lacked the Azimuth indicator and range quadrant. Since the M10s get used as artillery a lot in the MTO, they would like replacements to have them.

    M10 in Italy.
  • Replacement gun tubes – The using arms were very annoyed, that all type of gun barrels from machine gun and mortar, to tank and artillery, were dispensed at a very miserly rate.  The using arm argued replacement barrels should be bought at the rate that took into consideration how much ammunition for the same weapon was produced.
  • Improved fire control for all relevant vehicles –  They wanted built-in rangefinders, or portable ones supplied. Better periscope and telescope sights and all vehicles that could be used for indirect fire to receive the full suite of tools to perform the task.   I had never heard that some Shermans did not get these automatically. I’m not sure why some Shermans and TDs didn’t have the Azimuth indicator M19 and elevation quadrant M9. Maybe the crews dumped them to save space, maybe the tanks were rushed and built and approved without them I’ll try and find out. They mention 75% of the tanks in England had these items, but less 50% had them in the MTO.  Tank units were much more commonly used for indirect fire in the MTO than they would be in the ETO.
  • Engines –  The R975C-1 was getting around 200 hours before needing replacement. This was fine with the using arm, though they would like 60 to 100 more horsepower.  The R975 needed little maintenance to reach the expected 200 hours and many run much longer.  The lack of liquid cooling system has some advantages.
  • Powertrain –  There was a higher than expected rate of clutch failure in the desert campaigns. The clutch system was also improved on the production like with improved leverage to lower the clutch pedal pressure. Many MTO units did not receive the improved clutches or linkages.  The better clutches lead to better transmission life and better shifting, and even without the improved clutches, transmission life went up in Italy.  The powertrain offered excellent service and generally outlived the engines by several overhauls if not damaged.
  • Crew comfort – the Driver and Co-drivers seats in the Sherman were found to be ok, but higher seat backs were requested along with deeper seat cushions. The Gunners seat was found to be ok but could use the same improvements as the driver’s seats but the Command and Loaders seats were deemed all but useless. These would be improved in the later models of the Sherman and various TDs.  Crews do not use their seatbelts, fearing it complicating bailing out, and more padding inside was not wanted because the crews felt it was a fire hazard.  The M4 and M4A1 tanks were praised for good ventilation. There was also some discussion about the value of turret baskets, and if they were needed at all.
  • Ammo Storage – The early Sherman ready racks in the turret were well liked by the using arms, but they felt the sponson and hull ammo racks were no good and didn’t support the 75mm Shells enough. They would often separate and dump a bunch of gunpowder inside the tank making a deadly mess to clean.  The using arm tends to stuff the tank with extra rounds, adding to the shell durability problems. These problems would be addressed in the second gen improved hull tanks.
  • General storage – The current storage space on the Sherman was deemed ok, but better, easier to access bins were requested. They also wanted any storage in the floor to be resistant to getting filled with dirt or water.
  • Machine guns – The bow machine gun saw a lot of use, but its usefulness would be improved by a sighting system. One was in the works, but not at the point of this report.  The M1919 machine guns, both bow, and co-ax were reliable as long as the crew was careful with the ammo. Long road trips could vibrate rounds loose in the belts and cause problems, but under normal conditions, this was rarely a problem with well-trained crews.  The crews wanted a better adjustment method for matching the co-ax gun to the gunner’s site, the current one was not very good.  The .50 AA mount was not well liked or considered important. Requests were made for a better mount for ground targets.
  • Turret hatches – The current split hatch was deemed ok, but the crews like the looks of the new all around cupola and were also enthusiastic about a loader’s hatch on the new 76 armed tanks.
  • Armor – There does not seem to be a consensus on how much armor a tank should have by the using arms.  Armored Force troops felt the current level on the Sherman was fine, but wouldn’t mind more as long as it did not negatively affect flotation, maneuverability, and speed. ♠The British generally wanted heavier armor than the US Army.    ♠♠Combat in Italy showed the differential was taking more hits than anything, and another request was made for add-on armor for the area.
  • Sand Shields – The general consensus on these was they were useless in any theatre and needed to be redesigned. They needed to be easier to install, and designed to not trap mud.
  • Flotation – The using arms wanting tanks around 10 pounds per square inch. This was very optimistic since even the HVSS Shermans came in around 11 PSI, the basic 75 VVSS Sherman around 13.  It seems the Germans flooded fields in Sicily and Italy when they retreated, and Shermans got bogged down most of the time.  They offered the suggestion of just stretching the Sherman since more length would help, and the British M4A4 tanks, the longest production Shermans, had no maneuverability issues.
  • Maneuverability –   In the US Army there was a desire across the board for more maneuverability, in tanks. One thing to keep in mind though is the tanks in the MTO were older and most had single anchor steering brakes, the double anchor made the tanks easier to maneuver requiring less lever pressure. The ability to skid turn was not something US troops seemed interested in.
  • Accessories – The troops had a lot of feedback here. ♠ The instruments and gauges in medium tanks were not good quality, if they worked they didn’t work long. Oil pressure gauges fail, and no one worries about the motor until both oil pressure gauges die and a low oil pressure light comes on. This seems to be US feedback, I don’t recall hearing complaints from the Brits about Gauge quality. I wonder if the different tank plants sourced gauges from different companies. ♠♠ The compasses on US tanks would not stay calibrated. This would be a very annoying problem but eventually solved on second gen Shermans. ♠♠♠ Armor for the air cleaners on the M4 and M4A1 comes up again. ♠♠♠♠ The Auxiliary giving good service, and are well liked, but the using arms would like the area around the fuel tank filler for the Aux motor to be waterproofed better.  They also noted replacements were hard to come by.
  • Modifications –  ♠ The jist on this one was, in many cases modifications can be seen by inspecting a vehicle, but in others, access panels or more might have to be removed to check. The using arms proposed a record imprinted on a brass plate, attached to the vehicle, listing all the modifications that had been applied. ♠♠ They also wanted to emphasize that they did not want any modifications that would not ‘materially increase  the efficiency of the vehicles’
  • Development – The using arms were curious about the items in development, and finding out a large organization was working to improve almost everything was a morale booster. There was also interest in the T-20 series and if any test vehicles would be sent over for some for feedback like the M4A1 prototype has been.

 

Information and feedback on future equipment. 

  • The M4E6 or pre-production M4A1 76w –  ♠ This improved version was well liked by everyone who checked it out. The bigger turret was a big hit, though not much bigger, it seemed roomier. ♠♠ The improved fire control gear was very well liked and considered an ‘outstanding improvement’.  The 76mm gun was well liked, and everyone seemed to agree needed. ♠♠♠ The only real concern was the less effective HE round, but it was hoped they would make a better one.
  • The M18 76mm GMC –  The first and bad impression this vehicle lefts was it had no armor, and seemed very mechanically complicated.  The fire control gear was well liked. When the vehicle was demonstrated, the tracks and unthrowable tracks also got a lot of attention.  No one was sure if the speed would be useful, but the maneuverability was well liked. ♠ The same story with interest in deployment, not as a replacement vehicle, but fulling trained units from the ZI would be ok. ♠♠ This vehicle was not wanted by M10 units already deployed. Units equipped with it in the ZI then deployed were better received, the M10 was still more popular.  An M10 with a 90mm gun was the preferred replacement.
  • M4A3 75W – Even though the Ford GAA was a big improvement, it was not enough of an improvement to take them on as replacement vehicles. They were fine for them to be brought with units already fully trained on them.
  •  The M1 Dozer blade kit – This kit was an instant hit and would have many uses, including clearing rubble after heavy artillery reduced a strong point.  Currently, this has to be done by an unarmored bulldozer and casualties were high.  it was hoped they would work well enough to help tanks dig in or SPG prepare a position.  ♠ Through testing, they found this kit could be installed on any Sherman tank type.

This report goes into detail in the appendixes listing all the items demonstrated, and where they were demonstrated. They also include data on how many of the various items demonstrated were ordered by the various theatres.

I think it’s pretty clear the MTO was a backwater. The general shortage of spare parts in the MTO and a shortage of personnel to staff the proper echelons of repair and salvage system are also indicators of this. As they got ready for the June of 44 landings, the troops in England would be getting top priority and supplies and spares.

There is a lot of info on other weapons like artillery and small arms, not directly Sherman related and therefore, uncovered here. The report is definitely worth a download and re through.  I think it offers a good insight into the thinking involved on not swapping to 76mm armed Shermans before the Normandy landings.

 

#61 Storage Ammo and Everything Else: The Army packed a lot of Gear and Tools into the Sherman, along with the Ammo, Guns and Men

Storage Ammo and Everything Else: The Army packed a lot of Gear and Tools into the Sherman, along with the Ammo, Guns, and Men

When most people think about a tank, wait, well, most people don’t think about tanks, but when people who think about tanks think about them it’s the gun, the armor, the motor and it running around doing tank things that they think about. That’s not all that a tank is about; a tank is also about storing things, lots of things. Not just ammo, I mean sure, thousands of rounds of MG ammo and over 100 main gun rounds on late model Shermans, but even after the crew had packed all that stuff in, there was still a hell of a lot of other stuff they carried around. The tank had everything it needed to be maintained by the men it was issued to, including manuals, and a limited number of common spare parts for certain components and as much gear the tankers could accumulate to make their lives easier strapped on outside too.

M3 Lee ammo chart
A chart from the M3 Lee manual, TM9-750 showing the internal ammo layout

There are at least 61 hand tools used for maintaining the tanks automotive components.  Most of these tools were stored in a tool bag behind the driver. Some items like the non-magnetic screwdriver for adjusting the compass were stored in brackets on or near the device they were specifically for.  The oiler was mounted on a bracket by the assistant driver. He probably used it a lot. The huge track adjusting wrench and all the pioneer tools were mounted on the hull on the outside of the Sherman with the 20-foot long tow cable. The tanks weapons, including the main gun, also has a bunch of tools specific to them, also stored in the tank. These included combination wrenches and other special tools to maintain the machine guns, and an eye bolt and breach removing tool for the main gun adding between 6 and 10 more tools.  These tools were stored in a toolbox or a spare parts box. The grease gun, or gun lubricating, was mounted on the right rear lower hull, under the turret basket. It had an extension hose stored with it, and probably tubes of grease. This is what the crew would use to lubricate all the grease fitting that just about anything that moved had.

Шерман-1 (2)
The crew of an M4A1 (76)W Sherman load all the stuff that comes with a freshly issued tank into it.

Now the crew had to pack in the communication gear.  The tanks radio antenna broke down into 6 parts including the case and was stored on the blanket roll rack on the rear of the tank on late model Shermans. The early Sherman manuals do not list a location for them that I can find. There was also a flag set, M238, it had its own bracket on the right side of the turret.  This flag kit came in a case, had 3 flags, red, orange, and green, and 3 flagstaffs.  You also had the radio setup in the back of the turret that was technically removable.  The radios also came with a spare parts kit, small tool kit, and spare tubes and a crystal box to change frequencies.

75ID_Riedwihr_45 (1)
An M4A3 (76)W tank with a lot of stuff stored on the back

The tank was issued with 12 signal flares (they shoot up in the air), and they were mounted in their own box on the battery box. There were 3 white star parachute flares, 3 white star cluster flares, 3 amber parachute flares and 3 green parachute flares. Then there was the panel set. The set, I think was the big orange panels they put on the rear deck, so attacking fighter-bombers could tell US tanks from German ones, came with two panels, and two cases for them. They were also stored in the blanket roll on the foldup shelf on the rear of most late model Shermans.

The Sherman had two fixed 10 pound CO fire extinguishers that could be triggered from inside the tank, and outside if you knew where the pull handles were. They also provided the crew with 2, four pound CO fire extinguishers, on mounted on a bracket on the right side of the transmission, and the other mounted on the rear of the turret basket.  They also supplied a small decontaminated apparatus, called the M2, essentially a 1 ½ quart fire extinguisher, filled with a decontaminating agent instead of fire retardant. These were issued all the way into the sixties as a way to clean something like mustard gas residue from the areas of the tank the crew needed to touch. It was stored in a box in the hull, and probably got thrown away a lot.

The crew’s needs were taken into account, and there was a specific storage location inside the tank for 2 days of rations for the five-man crew. Each crew member also had an M1910 canteen mounted near their position.   There was a ration box in the right rear sponson, and it could hold either, 30 boxes of “K” rations,  60 cans of “C” rations or 2 or the much larger “D” rations. There was a small 1 burner Coleman stove stored with the rations. You see an awful lot of pictures of Sherman tanks and other AFV with a lot of ration boxes tied on the tank, so the crews appear to have liked to have more than two days food on hand. Of course, rations boxes are not bulletproof, and I bet it wasn’t all that uncommon to find shell splinters or bullets in the ration cans when stored outside.

We are not even close to done here, next up, sighting gear.  The tanks were issued with an M13 binocular set; this consisted of the M13 binoculars and the M17 case.  These were secured to the turret wall in its own bracket, near the commander’s position.  On late model Shermans, there was a box next to the radio that held 2 spare vision blocks for the commanders all around vision cupola. In a box behind the driver, you could find 10 spare bulbs for either the elevation quadrant or azimuth indicator. There was also a case for the Gunners Quadrant M1with its own bracket above the 5-gallon water can installed in the right sponson.

GUnners periscope

The periscopes and telescopes deserve their own section so here it is. There was a holder for the periscope in the periscope box in the turret, along with 3 periscope heads, for the M6 periscope. There were two hull periscope boxes with the same contents. There were 6 more periscope heads on the bracket for the driver’s hood for a total of 15 spare heads.  I’ve read several accounts where both the Germans and Japanese aimed at the periscopes and vision blocks to blind the tanks.  In at least one case in the Pacific, the tanks ran out of spare heads during the battle and were blind without opening a hatch. I bet periscope heads were popular as an extra spare on the tank.  Now, that was just heads, there were 12, M6 periscopes in each late model Sherman. Six mounted in in various places, one in the driver’s hatch that rotated, and a fixed one in front of him. The co-driver had the same layout, just on the other side, he used the hatch or fixed periscope to aim the bow machine gun.  The loader had had a rotating periscope at their station, and the commander had one in his hatch. There were two complete M6 periscopes in brackets on the turret walls, one near the loader, and the other by the commander. The amazing piece of American tank engineering, the driver’s hood holder, stored four complete M6 periscopes, along with all those spare heads and the drivers hood!

GUnners periscopeII
This is the predecessor to the M4A1 periscope

The gunner had his own special set of periscopes. He had an M4A1 periscope with telescope M38A2. On late model Shermans this was the auxiliary sight but allowed the gunner to have a nice wide field of view to find the target, the commander was handing off, mounted in his fixed periscope. He had a complete spare M4A1 periscope in a box on the floor by his feet.  They did not give him a spare telescopic sight, in late model Shermans, the M70F was used, and it was mounted on the gun mount. He also had a series of lamps to illuminate the reticles of the M70F and M4A1 sights. He also had lamps for the M1 quadrant, and another for the M9 quadrant.

the drivers hood

Oh, we are not even close to done here people, so hang on, it gets even more exciting when we get to the ammo storage and storage changes in a few paragraphs.  Anyway, let’s cover some more ‘general equipment’, before getting to ammo storage.  Let’s see, the tank had 5 M1936 OD canvas bags to store much of the gear that’s been mentioned, and 1 tool bag for most of the tools listed, stored behind the driver. There were 3 flashlights TL-122 on brackets around the turret, one near the commander, one by the gunner and one by the loader. They carried 12 spare batteries in box C101039. This is the same box all the lamps for the gunner’s sights went.  There were also 5 safety belts for the crew’s seats, it may not seem like a vehicle that doesn’t hit 35mph would need them, but off road, I bet they were handy.  The tank came with an 18-quart canvas bucket that was stored in the right sponson.  There was a special inspection lamp stored in the toolbox. The spare bulb was stored with the other spare bulbs in box C101039.  The Home light auxiliary motor had its own accessory kit, it was also stored in the sponson toolbox in the right front sponson.  This little kit had a spare spark plug, and the rope and wood pull handle to start the unit if the batteries were dead, plus a set of tools to maintain it.

M4A2 early storage
M4A2 ammo storage. Diagrams like this seem to have gone out of favor in the later manuals, as none of them seem to have them.

The Army liked to make sure a tank crew had lots of stuff to read, so they dedicated a small compartment in the right rear sponson for manuals. The manuals ranged from the one for the Homelite generator TM9-1731k, the spare parts list for the tank model, SNL G-104 in the M4A3s case, to manuals for both machine gun types FM23-50, and FM23-65, the manual for whatever main gun the tank had, and the mount it used. There was a manual for the model of the Sherman, TM9-759 for the M4A3, TM9-731B for the M4A2 etc. If there was a system on the tank the crew was expected to maintain, there was a manual available to tell him how to do it. I’m sure in some cases what actually got to the troops with the tank when it was finally issued varied a lot though.

Ok, now for the guns and ammo, as we know, a Sherman could have the M3 75mm gun, the M1A1/A2 76mm gun or the M4 105mm Howitzer. They all also had 2 and in some early models 3, M1919A4 Machine guns and one M2 HB machine gun.  On many models, there was a two-inch smoke mortar as well.  Then there were the personal weapons of the crew, on late model Shermans, 5 M3 .45ACP submachine guns were supplied, on early Shermans, a single M1928A1.  Each crewmember was issued an M1911A1 .45 ACP pistol as well.  These weapons, biggest to smallest all had kits to keep them working, and for the machine guns, they carried a lot of spare parts for known parts that wear on Browning machine guns. These spare parts and tools were scattered around in various tool and parts boxes.

US-SMG-M3A1-Grease-Gun-right
M3A1, five of these were issued with the tank
M1911A1
M1911A1, each crew member had one of these as well. One of the finest handgun designs ever made.
Submachine_gun_M1928_Thompson
Early Shermans had only one of these.

All these weapons needed ammo, and in the main guns case oil! This all had to be stored in the tank. The chart below breaks down the changes in ammo loadout for all the weapons on the Sherman, as the tank went through production changes. The earliest Sherman tanks had ammunition stored all over the vehicle in ammo racks with no additional protection.  Ammo was placed in sponson ammo racks, with some around the base of the turret, and in a floor ready rack.  More was stored under the floor. These early tanks had a fully floored, and screened in turret basket, with only two sections open to the hull. On these early Shermans, and we could be talking, an M4, M4A1, M4A2 or M4A4 most of the direct vision tanks would fit into this category.  These tanks, once the ammo around the base of the turret, and ready rack were used, would have to rotate the turret so the openings I the basket matched up with the hull racks, and or co-driver so he could hand in ammo from the rack near him.  The idea behind the full turret basket was to protect the crew from getting their limbs severed by the rotating turret if a crew member stuck it in the wrong place.

Sherman tank ammo loadout chart

As soon as the Sherman saw extensive combat use, it was clear, they were prone to fire. This was nothing new, every tank was prone to fire, and the Sherman had a tendency to burn catastrophically often launching the turret in the air. When the Army did a study into why this was the case, they found the main gun ammo was the main cause of catastrophic fire losses.  When you take a look at the ammo layout chart in the other image, you can see with the ammo stored, in unprotected internal bins all over the crew compartment, an ammo fire was going to be common problem.

M4A4 small hatch storage
This is an ammo layout diagram for the M4A4 tanks, this should be similar to all small hatch early non wet setups before the extra armor was added over the ammo bins.

The first try at a fix for the problem started pretty fast.  The fix was to remove the unarmored ready rounds from around the base of the turret, and reduce the size of the floor ready rack and to make it armored. The hull ammo racks were all covered in armor, and extra armor was added to the outside of the sponson racks on both welded and cast hull Shermans. On late production cast hull tanks, the thicker armor over the sponson racks was just added to the casting.  They managed to keep the number of main gun rounds pretty consistent even with these changes. Another aspect of the early fix was the removal of the turret screening around the turret basket. The ammo rack changes along with some other improvements were offered in kit form to US tank units already deployed, and it was eventually incorporated into the production lines, and tank overhaul facilities. Many Shermans in British use did not see these get these improvements.

This M4 composite seems to be under fire, and has a lot of junk on the back. Notice the soldier looking at the camera.
An M4 composite hull tank with a lot stuff loaded on the back.

The real big change in Sherman storage came when the hull changed from the small hatch to large hatch configuration, though all the late model M4A2 tanks with large hatch hulls and 75mm turrets still got the dry ammo storage setup with add-on sponson armor. The other exceptions are the M4 and M4A3 105 tanks, they had their on dry storage setup. The M4 Composite hull tanks with large hatch hulls also kept the dry storage layout.  So, the M4A1 (76)W, M4A2 (76)W, the M4A3(75)W, The M4A3 (76)W tanks all had the improved wet ammo racks. This change included moving all main gun ammo into the floor of the hull under the turret. These ammo racks were also surrounded by water filled jackets. Early production wet tanks retained the turret basket, and had hatches that could be opened to access the hull ammo racks, later they only installed a half basket, and eventually removed the basket floor entirely.

Укладка-Шерман
A loader checking out the ammo loaded in the wet storage on an M4A3 (76)W tank

On early Shermans a lot of stuff other than ammo was stored under the turret basket, in the floor, were the ammo was now going. This included the batteries, and a generator setup on some models. Also many of the items listed in the early part of this article were stored in the hull floor. These items including the batteries were moved up into the sponsons. The generator was moved to the rear of the transmission.  While making all these changes, they managed to pack even more ammo into the 75mm wet Shermans!

US_3rd_Armored_Division_M4_Sherman_Tanks_in_Action_in_Belgium_1944
Loads of stuff on the back of an M4A1

So, when all is said and done, if you take into account each round of ammo, a Sherman has nearly 8600 items packed into or onto it, officially. Granted, 7500 of that number is ammo, that still leaves 1100 items stored in or on the tank the crew had to keep track of  and I’m sure I didn’t take some things into account. You also have to think about all the personal gear the crew would have stuff in and on the tank. Anything they didn’t want shot or possible stolen had to be stored inside, even with all the official stuff in the tank, the crew would find places to stuff their most valuable personal things.  Less valuable things, like their uniforms and anything they decided to keep that couldn’t fit, was all hung outside.  If you look at late war pictures of Shermans, they are covered in stuff tied down on their rear decks. It’s no secret US troops were fond of taking souvenirs, and it got pretty rampant once they got into Germany.

20--1AD in Italy-X3
Just tank in all the stuff around this M4A1 75

Sources:  Hunnicutt’s Sherman, TM9-752, TM9-731G, TM9-759, TM9-731B, TM9-754, TM9-750, TM9-748, TM9-745