What Does ACP Stand for?

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We’ve had a bunch of discussions with our friends about guns. Many of them, as you can imagine, are totally against them, while others think they should be allowed as long as you know how to use them and don’t have any mental issues. And they both make sense. 

We personally have always been drawn to guns: there’s just something about shooting at the range, and learning about guns is very exciting and interesting. Thus, we always want to learn more. 

But while reading about weapons we’ve often encountered the abbreviation ACP. And at first, it was really confusing: “ What does ACP stand for?” – we wondered, “And what is it even?”. So you know what that means: we had to do even more research, and figure out what is ACP ammo.

And now we would be glad to share everything we’ve learned with you so that you could also have a clear idea of what does ACP mean.

What is ACP?

Many of you have noticed ACP written on ammo and firearms.  But, generally, when you just enter the world of firearms and ammunition you have plenty of questions, including those about ACP ammo. Don’t feel bad about it, though, because even those who grew up in this world can be confused by the lingo and acronyms and abbreviations.

So what does ACP stand for in ammo? In simple terms, it means Automatic Colt Pistol. To be more specific, the letters ACP are used to describe cartridges that John Browning designed for Colt’s semi-automatic pistols. 

And there are a lot of different cartridges, all are pretty similar. For instance, we have .25 ACP, .32 ACP, .38 ACP, .380 ACP and .45 ACP. Nowadays, there are still plenty of agencies that use this type of ammo. For example, it is very popular among FBI, HRT agents, SWAT e.t.c. It is because it is a very powerful and highly accurate bullet.  This ammo proved itself in the battle, too. It was used in many wars in which the U.S participated such as World War I, the Iraqi war, etc. It is still used today.

.45 ACP Overview

Okay, now when we covered the ACP definition it is time to go into a bit more detail. So, let’s see what the .45 ACP meaning?  Well, it is the most known and popular ACP ammo which doesn’t come with a rim. That was not the standard for ACP.  .45 ACP is a large caliber and takes a lot of space in the magazine. According to the story, which is essential when you are trying to understand what is .45 ACP ammo, Browning’s initial idea was to make a smaller caliber – 41. But the military officers said that they need a .45 caliber to stop the enemy forces. Browning then redesigned the original .41 and turned it into a .45 that is still used today.

Other ACP Ammo

So we explained what does ACP stand for in pistols and what the most known ammunition is. But there are also plenty of other ACP cartridges too. For instance:

.25 ACP

These are small bullets that use blowback pistols. They were created in 1905. They have a straight wall and are semi-rimmed. After the 1990s people almost stopped using it. The main problem with this ammo is that it is not very accurate. It is also essential to say that it is not powerful. Another reason why people aren’t using it anymore is that the 1968 Gun Control Act limited the importation of guns of a certain size. And it just so happened that most of these banned guns did use .25 ACP ammo.

.32 ACP

It is also a semi-rimmed cartridge. It is older than .45 and .25 because it was produced in 1899. You can also find it as 7.65x17mm SR Browning and 7.65 Browning Short. It is a compact and light bullet. Some people think that it can’t take pride in stopping power. Nonetheless, this ammo is still used by police and military forces all over the world. The handguns that use this ammo are ideal for concealed carry use. It comes with more velocity than .32 S&W. The guns that use this bullet can kill small game. However, if you want to use it for self-defense, you can do it only at a very close range.

.38 ACP

If you see the ammo labeled as 9X23mm SR or .38 Auto, keep in mind that it is the same as .38 ACP. It is again a semi-rimmed cartridge and it was initially designed for ColtM1900. There was also a .38 Super designed in 1929. This bullet offered higher pressure loading. .38 ACP was loaded in brass, while the Super variation was loaded in nickel. Many people confuse .38 ACP and .380 ACP. Although they are similar in diameter, there are still some major differences between the two. For instance .38 Super has a much bigger incredibly high basaltic energy.

.380 ACP

Same as. 45 which were used for the best 1911, this cartridge was also rimless. Like others, it was designed by Browning. It first appeared in 1908. You can also find it as 9mm Browning, .380 Auto, 9mm Browning Short. This ammo has been used for hunting. However it is also proven as good ammo for self-defense, plus it’s pretty popular among the military and police. 

These bullets, however, don’t penetrate more than 18 inches. If you want to use it for self-defense, you should know that it performs best at close range (less than 3 yards).

Is ACP worth it?

Well, there isn’t a straightforward answer to this question, is there? It depends on you! But is ACP good? Absolutely! And interestingly, although some would argue differently, it is still pretty popular ammo. The benefit here is that this cartridge has good stopping power without having a lot of recoils. Also, this bullet will expand equally well as 9mm. A quality .45 will go about .64 inches in its target. The handguns that use this bullet have pretty large magazines. They are compact which makes them easy to carry, especially as concealed weapons. Other than that, the bullet has less recoil which is a great advantage when you are a beginner. 

It is also necessary to say that although .45 ACP is primarily used in Colt, many other guns use it too. For instance Smith & Wesson M & P Shield, Sig Sauer P220 Legion, Glock G 21, Walter PPQ, etc. 

Are There Other Companies That Put Their Name Into Calibers?

Of course, everybody has heard of Colt and probably these ammo calibers that we mentioned in the text. However, it is essential to say that Colt isn’t the only company that used this strategy. You’ve maybe heard about .38 SIG which was manufactured by Sig Sauer. But there are others, too. 

  • .300 Winchester Magnum (7.62x67mm)
  • .30 -06 Springfield (7.62x63mm)
  • .308 Winchester (7.62x51mm)
  • .40 S&W (Smith & Wesson 10 mm, short)
  • .45 GAP (Glock Automatic Pistol, similar to .45 ACP, but a bit shorter and wider)


As we mentioned, the language related to firearms and ammunition can be confusing even for experts, let alone for people who just became interested in it.  However, we believe that understanding what ACP ammo is should be considered as part of general culture! Now when you know what does ACP in .45 ACP stand for you can easily figure out if these cartridges are for you. 

Or perhaps you’ve used ACP ammo before? What are your experiences?