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.45 Auto vs .45 ACP

Discussion in 'Handguns: Autoloaders' started by WalkerTexasRanger, Dec 13, 2003.

  1. WalkerTexasRanger

    WalkerTexasRanger New Member

    I am new to .45s, is there a difference between .45 Auto and .45 ACP ammunition? I will be firing in a new Springfield 1911A1 - Mil-Spec.

  2. GunNut

    GunNut New Member

    Nope. They are the same.

  3. Jim Watson

    Jim Watson Active Member

    ACP stands for Automatic Colt Pistol. Other makers are reluctant to put a reference to Colt on an offbrand gun. Ammo companies go along with them to get sales. Same with .40 S&W and .357 SIG, and many more older cartridges.
  4. WalkerTexasRanger

    WalkerTexasRanger New Member

    Thanks Guys, I appreciate the info.
  5. RWK

    RWK New Member


    The previous posters are (obviously) correct: the .45 ACP and the .45 Automatic are the same round. However, and for your edification, the .45 Colt (sometimes called the .45 “long†Colt) is an entirely different cartridge, used with tremendous success and great versatility in REVOLVERS for over a hundred years.
  6. Atticus

    Atticus New Member

    You'll not likely see them at the local sporting goods store...but there is also the 45 AR (Auto Rim) - it is similar to the ACP, but the case is rimmed, making the extraction of spent cases from a .45 revolver (without a moon clip) a tad easier.
  7. Jim K

    Jim K Active Member

    Not only is the .45 Auto Rim cartridge rimmed, but it has a doubly thick rim, intended to take up the space occupied by the rim and the moon clip. This allows the .45 Auto Rim to be used in revolvers like the Mode 1917 S&W and the Model 1917 Colt revolvers. It cannot be used, without alteration, in either an auto loading pistol chambered for the .45 ACP or in a revolver with conventional headspace. The .45 Auto Rim can, however, be adapted to revolvers chambered for the .455 Webley by trimming the rim down from the front, thus thinning it to fit in revolvers chambered for the .455 revolver round. With some extra work, it can be made to work in pistols chambered for the .455 Webley Auto Pistol cartridge by thinning the rim, cutting an extractor groove, and trimming the rim to a semi-rim.


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