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What is the difference between .45 auto and .45 ACP?

I've always thought that it was one in the same, but today I was over at Mid-Way USA's web site looking at ammo and saw that they actually specify a difference?

5 Answers

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  • Andy
    Lv 7
    9 years ago
    Favorite Answer

    Back in WW1 the military had a need for more pistols. In addition to the Colt 1911 Colt and S&W produced revolvers that fired the .45 acp. In the revolvers moon clips were needed(the gun worked without them but were hard to extract quickly) to allow easy ejection of the fired rounds. So a 45 auto rim cartridge was produced to eliminate the need for the moon clips. They are basically the same round except for the case.

    Edit I should add that the auto rim round was intrduced in 1920 for use in all the military surplus revolvers that were around. I have my grandpa's 1917 S&W revolver but I use the moon clips with it because it's cheaper to shoot .45 acp. I have a bunch of antique .45 auto rim ammo but I just hang on to it for the collector value.

  • Mr.357
    Lv 7
    9 years ago

    .45 ACP (Automatic Colt Pistol) is commonly referred to as .45 Auto. .45 Auto Rim IS different.

  • 9 years ago

    .45 auto is just a nice way of Glock not giving proper credit to Colt Mfg. They do the same to the .40 S&W & .357 SIG. The .45 GAP on the other hand is a separate cartridge altogether. I think that is what your refering to.

  • 9 years ago

    45 auto is 45 auto colt pistol- same same.

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  • Anonymous
    9 years ago

    one in the same

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