150 discarding sabot.

[cbo]

DRG said:
Given that info, allowing 3% of the ammo loadout to be APDS would seem fair. That would give 2-3 sabot rounds to each 57mm AT-Gun and would also require a slight adjustment to the service dates of a unit or two.

That's another way of doing it, of course. Still, given the very small amount available, it would seem unlikely, that all US 57mm guns had a small amount of APDS all the time.

Worth noticing is that both Charles' source and that SAIC study states that APDS was available for US 57mm guns from june 1944, even though the document unearthed by Kurt Laughlin seems to suggest that none was used. As I recall, there is also a reference to the British supplying US forces in Normandy with APDS buried somewhere in the Green Books, but exactly where eludes me at the moment.

It could be, that only 1st US Army had any, as it was the army that landed in Normandy. The action at Dom Butgenbach which the quote above relates to was fought by units from the 1st US division, a 1st Army unit which had landed in Normandy on June 6th 1944.

cbo

[CharlesM]

Agreed, but 2 pdr shatter problems were due to uncapped AP shot being used at German face-hardened armour in N Africa; the US 75mm M72 AP round had similar problems and later both the 2-pdr and US 75mm got APCBC rounds that cured this problem. At the 3900 or so fps a plain steel (i.e. non-tungsten) APDS core would shatter on impact. I have never been able to confirm that the 57mm APDS core was exactly 40mm, but it would seem logical.