=m.s.= 1943 20m.m.-mk-2

I picked up five shells from a local antique store I’d like to better understand what I have


Your 20x110mmRB (RB = rebated rim) Oerlikon MK-2 cartridge case was manufactured by Metal Specialties Manufacturing, Chicago, Illinois in 1943. The 20mm Oerlikon was used extensively by the U.S. Navy during and after WW2.

Pages from the U.S. Navy Ordnance Pamphlet No. 911, 1943


Typical gun and mount setup


Ammunition chart showing a typical loaded cartridge and color codes for the different types of projectiles used during WW2.


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Wow thank you very much very informative do you know what the =m.s.= Stands for? Thank you

M.S. = the initials of the cartridge case manufacturer i.e." Metal Specialties ".

Oh okay lol I feel like an idiot that was said in first reply lol thanks for all the help!