"Sub-standard US 75mm AP?" Topic

Niall Barr writes that the AP ammunition supplied for the American 75mm in the M3 and M4 was poor, shattering against German armour. The solution was apparently to take captured German 75mm ammo and use it to "cap" the US rounds. It fitted the US gun and the hybrid round was then much more effective, although most of the accumulated stock was lost in Tobruk.

I'd never heard this before, and don't quite follow it in several aspects. When a shell fails to defeat armour it's going as I understand it to do any of four things: bounce off, bury itself in the armour, make a gouge or tunnel in the armour from which it exits back to the open air, or break up. If the round couldn't defeat the armour, you'd expect one or more of those to eventuate. Is the implication here that the US round smashed on impact with armour that it should on paper have defeated?

I assume it just wasn't very good, otherwise there'd have been a Great American Shell Scandal and I've not read of one. I don't get, though, why an AP round would shatter, rather than bounce off. I've heard of squeeze-bore and sub-calibre rounds doing so, because they were travelling abnormally fast. So you had to use tungsten rather than steel for the head. But the US 75mm isn't a high velocity weapon.

On the mechanics of the adaptation, was the "cap" the entire business end of the shell, detached from a German round to leave a filled, headless shell case, and fitted to the shell case of a similarly de-headed US one? Or was there some piece at the tip of the shell that was removed from the German shell and fitted to the US one?

Was there a single common German AP round for 75mm, or were there different types for the L/24 versus the L/43 and L/48 weapons?

And finally, does anyone think this worth including into playing rules? Most that I have ever used abstract this level of detail away, i.e. it is embedded already into the effectiveness accorded the US 75mm.

Opinions gratefully read!

I don't know anything about using German caps on top but ASL (the boardgame) rates American ammo before 1944 as inferior in quality – something about old training rounds or something still in the pipeline. Would be nice to see if someone here has a primary source on that.

I've never heard of this usage of German caps on US rounds. Don't have refs to hand but I do recall that the Lee first went into action in Nth Africa with uncapped rounds for its sponson mounted 75mm. Certainly many of the rulesets on my bookshelf differentiate between the effectiveness of US 75mm capped and uncapped rounds.

It was done but not for this reason.

In Noirht Africa, the back and forth nature of the fighting gave the 8th Army the odd basecamp full of captured German ammo.

The Grant and Lee were entering service at this time. Think '42. They came with that wonderful thing called the 75mm. Based on the French gun of the Great War, it promised a common ammo with existing stocks.

Now what to do with a million odd rounds of German L24 75mm ammo. So by taking a good look and experimenting it was found that with minimal machining, it could fit into a 75mm shell case and be fired at similar ballisitc velocities and trajectories as the 75mm AP. It had the added benefit of a mild explosive component after it had penetrated the armour as well as the AP aspects. So, they went into production.

This came at a time when the 75mm was really just getting into massive number of use so it was also a useful way to boost ammo supply and use up what would have been an un-usable lot of a lot of ammo.

There really was nothing wong with any US 75mm AP rounds. The only true benefit was that bit of blast effect after penetration and mostly using up a warehouse full of ammo.

As I understand the bulk of it was recaptured by the Afrika Korps who could not use it at all.

There is a write up about it in Hunicutts' bible on the Sherman I think.

AP rounds could shatter on armour. Google shatter gap.
Is the article talking about just the cap, or is it the entire projectile?

I don't follow that troopwo.
If you happen to have a us 75mm case full of propellent then I would have thought it had a projectile stuck in it already.

Possibly a standing order that after firing off a shell, the cartridge would be retained and recycled with these new German AP rounds…?

Damon.

I found this same question asked on another older site….

<<As I had never heard of either the "mating" of the ammunition or of US troops being involved in the fighting I asked some friends on another forum and they came up with this from Hunnicutt and the link with reference to the troops.

R. P. Hunnicutt mentions this on pages 89-90 of his book on the Sherman, including a photo of a German 75mm APCBC round mated to the U.S. cartridge case compared to the U.S. M61 75mm APC round. Tests showed that the captured round had similar penetration to the M61 (and much superior to the interim M72 round), but that the explosive content of the German round was far more effective. About 15,000 captured rounds were converted and issued in time for Gazala, where 6,000 of them were promptly recaptured by the Germans when the supply dumps near Capuzzo were overrun.>>

the link referenced provides an error notation. link

Just like those folks who load their own pistol and rifle ammo, bigger rounds can be done similarly.

The projectile is removed and seperated from the cartridge case. It is lathed down one or two thousands of an inch until size appropriate and then it is inserted and crimped into a primed and loaded cartridge case. This was all done at a base workshop if not a factory.

Don't forget to ask any vet. Every casing from pistol and rifle right up to 105mm tank rounds are scrup[ulously collected from ranges to be sent back into the system for cleaning and reloading to save costs.

As for rounds shattering on hitting hardened armour.
Yes it will happen if the armour is thick enough.
For North Africa, thick armour was not a problem.

Test results of Cairo tests: