I acquired a quantity of 45 ACP military hardball ammo with the HS, R A 41 , copper colored primer with a dark colored sealant. Does anyone know if this was corrosive primed? It was loose packed in several old cigar boxes so I have no old packaging. Very clean with no signs of corrosion externally.

It is almost certainly corrosive primed, as, aside from .30 Carbine primers, the US used no other for military small arms ammunition until well after WWII. I think there was a small amount of .30-'06 ammunition made in Canada under US contract late in the war that used non-corrosive priming. It should shoot fine, I have several hundred rounds of it myself. Just clean your bore with hot water after shooting it.

The first Remington loads with non corrosive primers were made on September 1952 (Lot 5544).

Thank you DennisK and Fede. I figured it would be but was worth asking.
Thanks again.