<Tr> <Td> 185 gr (12 g) JHP, Underwood </Td> <Td> 1,100 ft / s (340 m / s) </Td> <Td_colspan="2"> 497 ft ⋅ lbf (674 J) </Td> </Tr> <Tr> <Td> 145 gr (9 g) Glaser + P, Cor - Bon </Td> <Td> 1,350 ft / s (410 m / s) </Td> <Td_colspan="2"> 587 ft ⋅ lbf (796 J) </Td> </Tr> <P> The . 45 ACP (Automatic Colt Pistol), or . 45 Auto (11.43 × 23mm) is a handgun cartridge designed by John Browning in 1905, for use in his prototype Colt semi-automatic pistol . After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol, being named . 45 ACP . </P> <P> During the late 1890s and early 20th century, the U.S. Cavalry began trials to replace their sidearm arsenal of issued . 45 Colt Single Action Army (SAA) in favor of the more modern and versatile double - action revolver in . 45 Colt . </P>

What is the difference between .45 acp and .45 auto
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