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Why does everyone say ".45 ACP"?

Discussion in 'General Gun Discussions' started by Boberama, Oct 4, 2010.

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  1. Boberama

    Boberama member

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    I don't like it as much as saying 45 Auto. Same goes for 380 Auto, 32 Auto, etc. Anything with ACP on the end.
    Sounds cleaner and more streamlined.

    Also, who spells 9mm as "9 m/m" anymore?
    questionmark.jpg
     
  2. TX1911fan

    TX1911fan Member

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    When did anyone ever write it as m/m? That makes no sense at all. The abbreviation for millimeter has never been, nor will it ever be, m/m.

    I prefer ACP myself.
     
  3. SuperNaut

    SuperNaut Member

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    I usually call it "John Moses Browning's Greatest Achievement, The Forty-Five Automatic Slash Autoloading Cartridge Slash Colt Pistol Caliber Slash Pistol Format." It is a mouthful, but it keeps irrelevant conversation to a minimum.
     
    Last edited: Oct 4, 2010
  4. hardworker

    hardworker Member

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    m/m is the engineering unit for strain. Pretty interesting concept when applied to ammunition.
     
  5. Jeff82

    Jeff82 Member

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    Because that's what it is?
     
  6. russ69

    russ69 Member

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    45 Auto or 45 Auto Rim? 45 ACP narrows it down a bit better.

    Thanx, Russ
     
  7. Flintknapper

    Flintknapper Member

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    Hmmmmmmm....I thought m/m was not any particular unit....but rather denoted "by mass", usually expressed as a percent.

    But....I've been out of school for a long time. :D


    Anyway, I also say .45 ACP (Automatic Colt Pistol)
     
  8. daorhgih

    daorhgih member

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    ¿ ¿ ¿45? ? ?

    To set it apart from 45LC, 45-70, et al. You are in good and polite company; you will tend to not be abused here. Ask away. Learn at your leisure.
     
  9. skipbadger

    skipbadger Member

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    I just call it Colt 45. Works every time...
     
  10. Trebor

    Trebor Member

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    Maybe because .45 ACP is the proper name for the cartridge? (Or at least the proper abbreviation).
     
  11. youngda9

    youngda9 member

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    "Why does everyone say ".45 ACP"? "

    I don't say ".45 ACP"...kinda distroys your entire theory eh?

    I say "45" or "45 auto".
     
  12. hardworker

    hardworker Member

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    Technically the unit m/m is unitless since since you're dividing a unit by itself. But in the engineering world that is the unit of strain.
     
  13. Ala Dan

    Ala Dan Member in memoriam

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    I most certainly call the .45 auto, .45 ACP; and as well the 9mm, a
    9m/m Parabellum; the last meaning of course, "for war"~! ;) :D
     
  14. younggun619

    younggun619 Member

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    45 ACP stands for Automatic colt pistol, It was a knew round made to be fired out of a semiautomatic pistol that was magazine fed, some what new technology for the time.
     
  15. daorhgih

    daorhgih member

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    Minor mistranslation:

    NOT: "9m/m Parabellum: for war!!!" but 9mm, military, as opposed to kurtz.
     
  16. oneounceload

    oneounceload member

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    Parabellum is comprised of two Latin words:
    "para" meaning "for", and
    "bellum", meaning "war"

    Actually, that cartridge's proper designation is its metric size: 9 X 19

    As to someone calling it 45 Colt - to many that indicates the 45 Long Colt, aka Colt 45 of single action army fame

    45ACP is the proper designation.........but then we Americans love to shorten everything to the least amount of syllables..............
     
  17. Oyeboten

    Oyeboten Member

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    Could also be called 11.5x22 ( .45 Autocolt)...and, .35 Calibre I s'pose ( 9 Millimetre ).


    I always preferred .45 Auto to .45 ACP also.


    mm is also a popular entertainer and singer I think...or maybe it's m&m or m 'n' m, pronounced "em-uh-nem"...which is also a candy, of course.
     
  18. james_bond

    james_bond Member

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    Also .45 ACP differentiates it from the more recent .45 GAP (a great answer to a question that nobody asked)
     
  19. BBQLS1

    BBQLS1 Member

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    .45 ACP as there are other .45 Auto calibers. IMO, it sounds right too.
     
  20. MMCSRET

    MMCSRET Member

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    My 1942 vintage Colt New Service double action revolver is stamped on the barrel
    "45 A.C.P." Maybe because Colts Patented Firearms Manufacturing Company named it what they wanted and probably knew what they were talking about.
     
  21. -eaux-

    -eaux- Member

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    Because that is what it is.
    .45ACP is already a short way of saying what it is: .45 Automatic Colt Pistol.
    when I hear "Colt .45" I assume that you are referring to ".45 Long Colt".
    An entirely different cartridge that will prove quite troublesome if you try loading it into your M1911.
     
  22. Dokkalfar

    Dokkalfar Member

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    mm is millimeters.

    m/m in terms of strain is actually (Δm)/m and is the change in length of an object divided by the original length. Based on stress pulling on it.


    So, I don't have much of a clue on how m/m would apply to any particular round.. esp when the 9 is the diameter...
     
  23. Boberama

    Boberama member

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    In Massad Ayoob's book "In the Gravest Extreme" he calls a 9mm a 9m/m.
    GravestExtreme.jpg
    I've never seen it anywhere else. Not even in pre-war books.
     
  24. Jim Watson

    Jim Watson Member

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    .45 Auto is what other companies call it so they don't have to put any reference to Colt on their knockoffs, even in abbreviation. Same reason Marlin and others got .44-40 into the vocabulary to replace .44 WCF (Winchester Central Fire.)

    When Savage was making pistols pre WW I, they actually had ammunition loaded with headstamp .380 SAP for Savage Automatic Pistol, even though it was the same in all respects as .380 ACP. And Colt cataloged revolvers in .38 Colt Special which differed from .38 S&W Special only in the slightly flat bullet nose.
     
  25. DoubleTapDrew

    DoubleTapDrew Member

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    How about calling 9mm: 380 Long, since .380 is called 9mm Kurtz (short) in some countries.
    I just say 45 but if I get a .45LC, or .45GAP or something I'll probably start adding ACP.
     
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