75mm German, US and composite AP shots and shells

[peeved]

Production began in January 1942 with 2,000 rounds of 75mm M72 AP-T. Manufacture of 75mm M61 APC-T began later in the year, but it is not recorded separately. It was not available in North Africa until after the Gazala battles. That was why they mated the German projectile to American cartridges (the M72 and M61 cartridge are exactly the same except for markings), in order to give them an M61 APC-T equivalent before it actually arrived.

It appears possible that the British received some M2 & M3 compatible AP ammunition from even earlier than 1942 back when they were cash customers. According to OMPUS p. 261 the foreign purchases of 75-mm ammunition APC, M61 & AP, M72 were 14 000 in November 1941, 20 000 in December, 19 000 in January 1942 and 47 000 in February (After that marked Program complete).

Markus

[Urmel]

But purchase doesn't euqate to delivery.

[peeved]

Sure but neither do the production dates previously given (at least when it comes to delivery to British & Commonwealth forces) which through 1942 denote M61 & M72 proof acceptance according to U.S. War Department (Ordnance Department) documents. Still even indirect data helps in establishing the time frame.

[Juha Tompuri]

Thanks Markus.

Hunnicutt, Sherman page 89/90:

During the development period of the APC M61, it had been necessary to introduce an interim round to meet the requirement for large quantities of armor piercing ammunition. This was the AP M72 monobloc shot. Rushed into production, this solid steel shot was variable in quality and tended to break up against face- hardened armor.
Tests carried out near Cairo in March 1942 against several German tank hulls re- vealed that the M72 shot was relatively ineffective against the frontal armor at ranges over 500 yards. A successful effort to provide effective armor piercing rounds resulted from the brilliant idea of Major Northy, an Australian serving with the British Royal Army Ordnance Corps. Early in 1942, about 50,000 tons of assorted German ammunition captured during the relief of Tobruk were moved to the Ninth British Army Depot along the Suez canal. Among this vast supply were many of the explosive loaded APCBC rounds for the Panzer IV’s 7.5cm Kampfwagenkanone (KWK) L/ 24. Major Northy noted that if the rotating band was modified, the German projectile could be fitted into a U.S. cartridge case and fired from the M3’s 75. Checking with Major G.B. Jarrett, an Ordnance ammunition expert with the U.S. Mission in the Middle East, he found that Jarrett not only agreed as to the feasibility of the project, but gave it his enthusiastic support.
The German projectile differed from its U.S. counterpart in having a much wider and thicker rotating band, but the basic dimensions of the round were essentially the same. A number of the German projectiles were removed from their cartridge cases and the rotating bands turned down to the U.S. dimensions in a lathe. The rounds were then success- fully assembled into U.S. cases and they chambered properly in the M3’s 75mm gun. These were explosive loaded armor piercing projectiles fitted with a base detonating fuze. This fuze was armed by the projectile rotation when the round was fired. Fortunately, the lathe rotation was insufficient to arm the fuze during the machining operation. Some of the converted ammunition was test fired against a Panzer III hull in comparison with a few of the new U.S. APC M61s which had been flown out to Cairo. Like the German round, the M6l was fitted with an armor piercing cap, but it was inert loaded since the development of a suitable base detonating fuze was not yet complete. The tests showed the penetration performance of the two rounds was identi- cal, but the damage resulting from the German projectile was much greater. Both penetrated the front of the Panzer III at a 1000 yards, but the German round exploded inside the tank. In combat such an explosion would almost always set off the stowed ammunition. With the approval of Middle East Headquarters, the new round was designated as the 75mm AP- Composite and conversion began at full speed. A total of about 17,000 rounds were converted of which 15,000 were the explosive loaded APCBC. The remaining 2000 were high explosive and smoke which were also modified as any reliable round was most welcome for the M3’s gun. U.S. AP M72 and HE Mk I ammunition was used to provide the primed cartridge cases and propellant charges.
Much of the old ammunition was found to contain variable weights of propellant so all the charges were dumped together, mixed, and re- weighed to insure a uniform muzzle velocity. The conversion work took two to three weeks and the composite rounds were sent forward before the action opened on the Gazala line in late May. No information seems to be available on what use was made of the new ammunition. About 6000 rounds were captured by the Germans in the dumps at Capuzzo during the retreat to Alamein. They were then moved to the German base dump at Tobruk where they were recaptured the following November

http://forum.axishistory.com/viewtopic. ... 5#p1703501

Regards, Juha

[Richard Anderson]

It appears possible that the British received some M2 & M3 compatible AP ammunition from even earlier than 1942 back when they were cash customers. According to OMPUS p. 261 the foreign purchases of 75-mm ammunition APC, M61 & AP, M72 were 14 000 in November 1941, 20 000 in December, 19 000 in January 1942 and 47 000 in February (After that marked Program complete).

Markus

Markus, good catch. However, although the M2 and M3 Tank Guns appeared in the Medium Tank M3 as early as July 1941, the only 75mm production was HE, Smoke, and Gas, until AP production began in November 1941. And M61 production did not begin until later in 1942; I'm still trying to pin down the date from Ordnance records.

[peeved]

The earliest documents on 75 mm AP (although for some reason called semi-AP shot) delivery to the British I've found are Defense Aid Program shipment notes from Weekly Statistical Summary; Report No. 35; February 28, 1942. No idea though if and when cash buy AP ammo was delivered.

Markus

[Juha Tompuri]

The British used the M61 shells they received without HE filler; they filled the cavity with some sort of concrete, which increased the shell's strength and increased penetration above what the Americans achieved in their tests.

https://forum.warthunder.com/index.php? ... man/page-5

Really?

Regards, Juha

[Richard Anderson]

The earliest documents on 75 mm AP (although for some reason called semi-AP shot) delivery to the British I've found are Defense Aid Program shipment notes from Weekly Statistical Summary; Report No. 35; February 28, 1942. No idea though if and when cash buy AP ammo was delivered.

Markus

Yes, those should be the M72 AP rounds shipped with the first Medium Tanks M3 sent to the British.

[avenger]

I recently picked up an M/72 AP-T slug. I understand it was rated inferior rather quickly in field tests, but is there any information on this variant actually being used in combat during the war?