Why does everyone say ".45 ACP"?

[Boberama]

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?

 

[TX1911fan]

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.

 

[SuperNaut]

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.

 

[hardworker]

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

 

[Jeff82]

Because that's what it is?

 

[russ69]

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

Thanx, Russ

 

[Flintknapper]

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.


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

 

[daorhgih]

¿ ¿ ¿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.

 

[skipbadger]

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

 

[Trebor]

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

 

[youngda9]

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

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

I say "45" or "45 auto".

 

[hardworker]

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.

 

[Ala Dan]

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"~!

 

[younggun619]

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.

 

[daorhgih]

Minor mistranslation:

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

 

[oneounceload]

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..............

 

[Oyeboten]

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.

 

[james_bond]

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

 

[BBQLS1]

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

 

[MMCSRET]

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.

 

[-eaux-]

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.

 

[Dokkalfar]

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...

 

[Boberama]

In Massad Ayoob's book "In the Gravest Extreme" he calls a 9mm a 9m/m.

I've never seen it anywhere else. Not even in pre-war books.

 

[Jim Watson]

.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.

 

[DoubleTapDrew]

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.