A little help please. I’m not well versed in the larger calibers, so I need some assistance with the ID of two unfired projectiles. These items came from a gentleman who worked at the Raritan Arsenal in New Jersey during WWII. The first is a 20mm projectile from either the 20x110 HS or the 20x110 Oerlikon. My reference materials are not precise enough to differentiate the two types. Steel body, zinc? pot-metal/white metal dummy fuze/nose cap all painted olive drab green, copper rotating band. Stamped into the projectile body is “MK 3 - 54 U” (might be a “J”) “LOT 1451” “MAT”. What does this go to and is it a practice projectile or “ball” or what?
Second projectile is from the US 37x223R and appears to be an AP-T. All steel body with wide copper rotating band and an aluminum nose cap/windscreen that is threaded to the projectile body. There are two notches in the projectile body that appear to be for staking the nose cap in place, but this has not been done. The base is hollowed out for what would likely be a tracer cup. There is not trace of any paint whatsoever on this projectile, and it appears to have never had any. The only markings at all on this item is the leter “Z” on the base of the projectile. I assume that the loaded round would have an all-black projectile with white stenciling? Supposedly, the gentleman who owned these items was a book binder by trade and worked at Raritan Arsenal in this capacity making technical manuals and such. Apparently, other workers gave him these projectiles and they were used as “paper weights”. Could these have been produced at Raritan? Could the 37mm be incomplete/unfinished, taken off of the production line? What is the correct nomenclature for the 37x223SR AP-T, what gun was it useed in and can any one post a pic of what the round looks like?