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37x223R cartridges for the M3 anti-tank gun, USA, WW2

pzgr40

Well-Known Member
Premium Member
Cutaway models of three shells for the American WW2 37x 223R M3 anti-tank gun.

20.000 M3 guns were built between 1939 and 1943, however on the western front is was considered to be too light to fight the German tanks. In the far east however it was adequate throughout the war as Japanese tanks were without exception lightly armored. It was used in many tanks, armored vehicles and self propelled anti tank guns. For instance: M5A1 Stuart tank, M8 Greyhound armored vehicle, the staghound armored car, Locust tank, Grant tank.

-The 37mm M51 APC-T shot consists of a solid -nose hardened- steel shot with a piercing cap and a ballistic cap on top of the nose. The piercing cap is made of mild steel and divides the force of the impact over the entire nose of the projectile, preventing it from shattering upon impact. The aluminum windshield improves the ballistic performance. In the bottom of the shell a hole is drilled into which the tracer composition is pressed.
The color of the projectile is black. Vo is 884 Mtrs/sec (2900 ft/sec).
The shell will penetrate 53mm (2,1”) plate of steel at 457 mtrs (500 yards) and 46mm (1,8”) at 914 mtrs (1000 yards) at a 30 degree angle.

-The 37mm M63 HE shell exists of a mild steel body, threaded in the bottom to receive the Base fuze M58. Around the firing pin an interrupted ring is placed in a groove, fixating the setback sleeve in the forward position. The firing pin cannot move forward and reach the firing cap. Upon firing, the sleeve is forced backward by the setback force, the interrupted ring is bent open slightly and falls into the lower groove. The firing pin can now reach the firing cap if it moves forward, kept in backward position only by a weak spring. On impact the firing pin is launched forward into the detonator by inertia. The shell is filled with 39 grams TNT. Color of the projectile is yellow.
Vo. is 782 mtr/sec

-The 37mm canister shot M2. It acts as a large shotgun and is very effective against groups of attacking infantry.
The projectile is build-up of sheet metal and houses 122 steel ball with a 10,5 mm diameter, cast in resign. The length of the projectile body is 160mm long.
Weight of the round is 1,58kg, the projectile weighs 0,88kg.
Vo: appr. 755 mtrs/sec.

Regards, DJH
 

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Very nice job as always DJH,
Beautiful sections and a great write up, i have always had a soft spot for these rounds and am still trying to complete the set, only taken 20 plus years so far, still time.
Thank you for taking the time to put the post together for us to see, best Weasel.
 
Added to the collection;
A squeeze bore or Jancek (Little John) cartridge for the 37 mm M3 gun. The M3 gun was adjusted so a T1 conical barrel piece could be screwed to the end of the barrel. (see pict.-06).
As one can imagine it was not a very popular adjustment as one had to screw this piece on the barrel during battle, allowing for armour piercing shells of this type to be fired only. Accidently firing a normal shell in the heat of battle would result in the barrel be blown to pieces. It was however possible to fire the squeeze bore projectile without the T1 adapter, however this had a negative influence on the penetration value of the projectile at longer distances.
One will understand that APDS -that was invented halfway the second world war- was much more popular as it did not require field adjustments to the barrel during the battle, did not cause excessive barrel wear due to high pressures, and had better results over longer distances.
The Projectile consists of a steel body with a tungsten penetrator. The outer sleeve is pushed inward thereby moving it down, filling the gap. The conical flange at the base is also bend inward, leaving a smooth body ø30mm shell after the projectile has left the T1 conical barrel piece.

Regards, DJH
 

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Great addition to the collection, and a lovely section. Thank you for adding it to the thread. Best Weasel
 
Your work is awesome Jaap, and I do not offer constructive criticism lightly. However, your simulated propellant in these rounds does not look anything like the actual material that I have seen. The manual shows tiny cylinders with multiple perforations.
 

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Thanks DJH, outstanding result! I did not even know about the existence of this round. May I ask what do you use for simulated propellant? Thanks.
 
Does anyone know if that 37mm squeezebore system was ever used in action? I have a vague recollection of reading that it was used by Locust airborne tanks, but nothing definite.
 
Hi M8, thanks for the feedback. I got my info from a TM long time ago when I still had these two halved cutaway models. I assume they must have drawn in a hatching which I took for propellant. However, other people drew it the same way, they must have used the same TM with wrong info. Do you think it's the smallest powder like in the .50 cartridges that is used in these shells? Than I will change the powder to correct it.
By the way, X posted a drawing of the cartridge on the Wk2 forum, to my surprise an August1945 drawing. (thanks for that X)
 

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The propellant used to reload this ammunition looks like this. It was manufactured in the 1980's for 105mm tank ammunition. I know some folks have WWII surplus M6 powder that was used in 37mm, but I have never seen the grains up close. The grains in the manual are much smaller than I would have expected for 37mm. So, the WWII propellant looked like the examples here, but were probably much smaller. These grains are 7mm or 1/4 inch long. They are dark green.
 

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Ok, I will start changing the powder in the correct powder type and replace the pictures. Nothing is as important as correct info
 
I have changed the pictures of the Shells for the following reason:
As "M8 owner" adviced me that the powder I placed in the shellcases was not of the right size and shape, I descided to change it
I got my info from an old TM, and by now I started to realize that the powder drawn in there was the stylized depiction of powder in a shellcase.
Therefore I have descided to replace the powder in the shellcases with -fake- powder that looks more like the real thing in shape and size.

Maybe the moderator of this forum chapter could replace the pictures in the Original posting with these new ones.

Sorry for the inconvenience.

Regards, DJH
 

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  • Pict.06 - 37mm  Squeeze bore cartridge for M3 gun.jpg
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An amazing amount of work, both times. Even down to the black powder in the primers. Fantastic job.
 
It is almost like you had that simulated powder just laying around and waiting for the job. At this point, I am wonder where you keep everything you have cut. You probably need a second house by now.
 
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