>>63986653 (OP)>nobody says .50 bmg despire .50 bmg being mounted variously on every US combat vehicle from 1939 to the present day.Small arms and even squad MGs do a minimal amount of actual killing. Heavy machine guns mortars and artillery have utterly dominated kill counts since WW1. If you want to talk about small arms specifically you're probably talking about one of the British or French empires musket calibers that stayed in service for a hundred years or more like British Land Pattern .75 or the French .69 Charleville
Those guns actually did the killing in many of their engagements and in the Brown bess's case it was THE GUN of the British empire for 145 years. Charleville for about 120. And those periods were bloody and full of Imperial wars that saw large european land campaigns with pitched field battles were thousands and thousands of men died.
Modern Firearms do a minority of the actual direct engagement and their primary purpose is keeping enemy forces pinned down so they can be flanked or bombed to death. Whoever shoots more wins and trying to pop up and shoot once you're suppressed is just begging for random sudden death. Think all those videos from syria of a guy moving into the open and just getting instantly schwacked, thats not a sniper he stepped into an MG burst.