At a recent gun show, I got introduced to a box of ammo which has the above label. Made by
Frankfort Arsenal, Feb. 1945. As the label states it is for " Non-Standard Velocity for Helmet
Testing." Rounds were fired at samples of every production run of US M1 helmets. If the round
penetrated the production lot was rejected.
These cartridges were loaded for 880 ft/sec to be fired out of a 10.5" barrel. The only gun in the
inventory with a 10.5" barrel, I think, was the Thompson Submachine Gun. A standard 230 grain
Thompson fired cartridge has a muzzle velocity of around 920 ft/sec. So these rounds were to
simulate being fired by a Thompson at a certain distance from the helmet and if the rounds did not
penetrate a GI helmet then the production lot passed. Any volunteers to wear the helmet?
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