The M2 Browning .50 (Ma Deuce), fires at such a low cyclic rate (not aircraft models), that most gunners can squeeze single rounds (they didn't use to be select fire, though that is available now). Standard barrel length is 45 inches. Mounted on the heavy land use tripod, it can be be very steadily aimed at a fixed target, and only takes a good optic and some zeroing time to get amazing accuracy. Carlos Hathcock mounted a straight 10X Unertl scope on one in RVN (the same scope they used on Model 70 Winchesters in RVN).
Here's Hathcock with his Winchester and Unertl scope. When he made his M2 .50 shot in RVN, it was at the time the longest sniper shot in history.
And on the .50
You can't load .50 BMGs in your Smith and Wesson .38 by accident either.
