Comments by "" (@RedXlV) on "Captain Carl Pelo's Model 1954 Prototype Semiauto Rifle" video.

  1. The 7.62x53R has a 7.85mm bullet diameter (compared to 7.92mm for 7.62x54R),53.5mm case length (compared to 53.72mm), 14.4mm rim diamater (compared to 14.48mm), and 77mm overall length (compared to 77.16mm). That difference is usually not enough to matter, though. Unlike some other not-quite-identical cartridges such as .308 Winchester and 7.62x51 or .223 Remington and 5.56x45, 7.62x53R and 7.62x54R also have identical maximum pressure. So a gun that can fire one can almost always fire the other. So why does 7.62x53R even exist? Apparently after becoming independent, Finland switched to smaller diameter (7.82mm) barrels when the original barrels of their Mosin-Nagants started to wear out. Why did they do that instead of replicating the existing bore diameter? No idea. I know they bought a bunch of new barrel blanks from SIG in the early 1920s, so maybe that's just what SIG had in stock at the time.
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