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The Italian SAFAT 12.7mm used a less powerful cartridge (12.7 x 89 - MV 765 metres per second (2,510 ft/s)) than the US .50 cal (12.7 x 99 - MV 2,910 ft/s (890 m/s) for M33 ball)
Also as Captain Thunderbolt mention on post 220 - the Browning .50 cal incendiary had...