More stuff I pulled out of the water #3

This is a 30 mm x 110 mm shell casing pulled from Chincoteague Bay in around 1992. The base is stamped: "1944 HP LOT 142 20 MM M21A1". It's hard to tell where this came from - probably not an aircraft since they were not shooting these big calibers out of aircraft until somewhat later, although surplus ammo may have been used later. The modern "Vulcan" on the front of an A-10 Warthog is 20mm.

Given the caliber and the length, this most likely came off of a Navy or Coast Guard gunboat in or shortly after WW2.