After the discussion on the sherman 75/76mm cannon it occurred to me that most WW2 US cannon were designed prior to the war or by another party entirely. US gun design seemed mainly interested in mounting changes. Just wondering if you can point out some I've missed. 50 cal ww1 design 20mm british design 37mm based off the German 37mm though not a direct copy by any means. 40mm bofors swedish license 57mm british design 75mm m2 based off a french cannon some mounting changes 76mm new US design 90mm ww1 design some mounting changes 105mm 1930's design some mounting changes Perhaps the naval arm was more prolific but my knowledge there is lacking.