A question that comes up often is what go ACP stand for as soon as it involves guns and also ammo. We see the phrase often, and also how it came around is a an extremely interesting story.

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In this article, I arrangement on comment that concern for you and also giving girlfriend the elevator of howACP fits into modern-day firearms. Here"s the an easy answer:

ACP = automatic Colt Pistol

Check out the video next if you want the rapid answer and also stick roughly for the remainder of the post if you want the complete scoop.

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Most the us understand this:

The creation of the automatic pistol changed the see of firearms.

But there to be a catch...

The advent of reasonably compact, slim semi-automatic pistols required a standardization the caliber.

Here"s why:

Many revolvers required rimmed ring that continued to be seated in the cylinder after gift discharged.

However, semiautomatic pistols, such as the Colt 1911, did not require rimmed rounds.

In fact, having a in salt that exceeded the diameter of the cartridge would cause the round casing to catch or snag.

The many notable example of this brand-new era of semi-automatic pistols is the Colt 1911, created by man Browning.

Browning well-known that the Colt 1911 required a ring that would eject after gift discharged and also would load conveniently into a magazine.

For those that have actually owned or shoot the total before, you know it takes a very certain caliber of ring – the .45 ACP.

This leads to the key question, i beg your pardon we will certainly answer next.

What go ACP was standing For?

The abbreviation stands for Automatic Colt Pistol. The dual an interpretation behind this abbreviation is:

inform the engineer or armorerinform the consumer

By tie to the round, it specified that Colt designed this round specifically for their pistols.

That is clever marketing, right?

The difference needed to it is in made indigenous an engineering standpoint and also for the consumer.

Browning labeling these new pistol ring – such together the .32 or .45 auto – as Automatic Colt Pistol rounds. This came to be abbreviated just asACP.

Same Caliber, various Bullet

Now, a round choose the .45 ACP is no interchangeable through the various other varieties of .45 caliber ring on the market.

A notable instance would be the .45 Colt – otherwise well-known as the .45 lengthy Colt.

The huge difference in between a .45 ACP and also a .45 Colt ring is 10 millimeter of included length come the long Colt and a protruding rim at its base.

This do the .45 Colt right for revolvers. The .45 ACP round to be made only for semi-automatic pistols.

Revolvers, such as the M1917 Revolver made by Colt, deserve to accept ACP rounds.

However, most revolvers are developed for rimmed cartridges and the ACP ring does not have a protruded rim.

It would certainly be attention to load a .45 ACP right into a .45 Colt revolver. It would certainly be terrible to pack a .45 Colt into a pistol that welcomed .45 ACP.

Both ring have various dimensions even though they are the very same caliber.

The loss of length on the .45 ACP also sacrifices the speed of the bullet. But, the .45 ACP is just one instance of quite a couple of Automatic Colt Pistol calibers.

Colt designed a huge variety the firearms. It came to be necessary to begin referring to each caliber by a system that made feeling for the company.

A couple of notable automatically Colt Pistol calibers include: .25, .32, .380, .38, and also .45.

All of this calibers room denoted v an “ACP” in ~ the end of them. However, this rounds are additionally referred to together “auto.”

For instance, if you walk right into a gun store and also ask the clerk because that a situation of .32 ACP or .32 auto, he will certainly hand friend the same case of ammunition.

There is no difference other 보다 which system a human uses to describe those details rounds.

It gets amazing when we consider how this rounds fit into the hand pistol arena.

Automatic Colt Pistol Calibers

The .25, .32, .38, and also .380 autos are an extremely compact, light rounds. The .380 ACP is 2 millimeters shorter than a 9 x 19 millimeter Parabellum.

This provides it really compact and easy come fit into smaller handguns such together the Bersa Thunder or old Walther PPKs.

The .25 ACP is just three soldier of a millimeter more comprehensive and one millimeter longer than the .22 long Rifle (5.6 x 15 millimeter).

This provides the .25 ACP really light round. The is mostly uncovered in highly concealable derringers and semi-automatic pistols.

It to be the initial an option of Ian Flemming when he started writing about James Bond.

He was later on advised by someone much more familiar with guns that the .25 ACP was an extremely underpowered round.

Speaking that underpowered—before innovations in the ar of smokeless total powder, countless of the automatically Colt Pistol ring were considered to be an extremely underpowered.

The .25 and also .32 ACP space still supplied by part European police forces. The .380 Auto is exceptionally popular together a concealed lug handgun caliber, but many people complain around the penetration that this round against ballistic gel.


Out of all of the rounds, the .45 ACP came to be the most notorious because it was used in the Thompson submachine gun and the Colt 1911A1 semi-automatic pistol.

It earn its ar in American nostalgia.

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The just round come no much longer be in active production is the .38 ACP.

The .38 ACP was an effort to lug the caliber indigenous the human being of detective revolvers come pistols.

It never really take it off. Sig Sauer newly attempted to carry the caliber ago in your line the pistols and also that ring is now well-known as the .38 SIG.

In state of stopping power and potential, the .38 has constantly been underpowered in comparison to its larger, much more powerful .357 Magnum cousin.

Colt Was no the Only agency to put Its Name right into Calibers

While we might recognize popular calibers such as the .45 ACP or .380 ACP, that is vital to establish Colt was no the only agency to usage this trick.

As discussed earlier, Sig Sauer produces firearms chambered in .38 SIG. A couple of other remarkable cartridges the bear your maker"s note include:

.300 Winchester Magnum (7.62 x 67millimeter).30-06 Springfield(7.62 x 63 millimeter) .308 Winchester (7.62 x 51 millimeter) .40 S&W (Smith & Wesson, a 10 millimeter short)