I thought you might be interested in looking at 7.62x51 is for a M14 7.62x54R is for a Mosin–Nagant.
https://forums.dayz.com/topic/178570-762x51-is-for-a-m14-762x54r-is-for-a-mosin%E2%80%93nagant/?do=findComment&comment=1890400
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