A Russian, writing many years ago, expressed confusion as to why the US Army tended to give the same designations to so many things. He believed it surely led to serious confusion. How many things were "M-1 (or M1)," for example? However, he mentioned that calibers had so much overlap. How many things were 75mm? Personally, I suspect he may have been overstating a point, since the Soviets used at least three different small arms cartridges that were .30 caliber or 7.62mm.
I believe I have mentioned before that while there are advantages to standardization and simplification in ammunition, it was theoretically possible early in WWII for a British light tank to require five different small arms ammunition. Some early tanks had a 15mm and a 7.92mm Besa guns, .38-200 for the crew's revolvers, probably .45 ACP for the Thompson they probably had and if there was an extermally mounted Bren, .303. But they probably didn't have a Bren and they probably rarely used their revolvers.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
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