What is .45? Auto? ACP?

[Kymasabe]

OK, stupid question here but here it goes. I've been a life-long 9mm shooter but recently picked up a nice Ruger P345. My question is, is .45auto and .45acp the same thing? I'm under the impression that they are...and I know they're NOT the same as .45GAP so no worries there. Just want to make sure I'm buying (and shooting) the right stuff.

 

[PT1911]

yup... same thing... you have (1) .45 ACP (auto) (2).45 colt and (3).45 GAP...

As long as you arent trying to shoot one in the other you are just fine...

 

[KyJim]

.45 Auto Colt Pistol is .45 ACP is .45 auto. The .45 GAP is an entirely different animal as is the .45 Colt (revolver round).

 

[dmazur]

Brief history of the .45 ACP

If you have a little time to spare, here's a link to a short history of the cartridge -

http://en.wikipedia.org/wiki/.45_ACP

 

[Badger Arms]

Ruger uses the caliber designation .45 AUTO because the alternative is:

.45 ACP (.45 caliber Colt Automatic Pistol)

Ruger naturally has nothing to gain from putting anything that says "Colt" on their own firearms.

 

[Kymasabe]

Thank you.

Thank you all.

 

[Seamusalaska]

You probably know this but you mentioned 9mm. The 9mm is the bullet diameter in millimeters and .45 is the diameter in inches. The ol' metric vs "King's English" debate. I'm sure someone here will correct me If I'm wrong.

 

[Kymasabe]

Yup, familiar with Euro sizing and American calibers.

 

[1858rem]

i think ACP stands for Automatic Centerfire Pistol.....where else does the 380 acp and 25acp come from?

 

[Cpt. America]

ACP- Automatic Colt Pistol.

 

[Hoxviii]

.380 and .25 acp were both first chambered in colt pistols as was the .45, hence automatic colt pistol.

 

[1858rem]

thats pretty cool, i was wondein why 9mm, 40 s&w, 357 sig an pretty much every other auto was not a ACP. i feel a little more knowledgeable now

 

[rondog]

I guess whoever invents them gets to name them.

 

[9mmepiphany]

yup...you invent it, you get to name it

GAP - Glock Auto Pistol

BTW: in your ACP listing, you left out the .38 ACP

 

[TehK1w1]

And the 32ACP

 

[Archie]

And, at no extra charge:

All the ACP rounds were designed by John Moses Browning. (As best my tired old memory serves.)

.25 ACP, adapted by the Europeans and called 6.25mm
.32 ACP, adapted by the Europeans and called 7.65mm
.380 ACP, adapted by the Europeans and called 9mm [insert European word meaning 'short'; Corto, Kurz or Kurtz, and so on]
.38 ACP, equal to the 9mm Luger and fore runner of the Super .38
.45 ACP

Kymasabe, you've already been answered. "45 Auto", well used by most everyone, is in fact a misnomer. The proper name of the cartridge is .45 ACP. It is sometime referred to as "45 Colt Auto" or "Colt 45 Auto", but those are also popular names rather than actual nomenclature.

But we live in an age where people don't really pay attention to detail and tend to invent their own language.

 

[The Lone Haranguer]

If the gun or ammo is labeled ".45 Auto" or ".45 Automatic," it is for the .45 ACP (Automatic Colt Pistol) cartridge. Curiously, to my knowledge only Les Baer labels their guns ".45 ACP," and no ammo makers do.

 

[JTQ]

And don't forget .45 ACP Auto Rim. Same ballistics as the .45 ACP, but with a rimed case for use in revolvers.

Don't use it in your P345 though.

 

[Deanimator]

.25 ACP, adapted by the Europeans and called 6.25mm

6.35mm

 

[ljnowell]

And don't forget .45 ACP Auto Rim. Same ballistics as the .45 ACP, but with a rimed case for use in revolvers.

Don't use it in your P345 though.

And 45 super. Same dimensions as 45acp, just more performance.

and 45 schofield.