A question that come up frequently is what go ACP was standing for as soon as it comes to guns and ammo. We view the expression often, and how that came around is a very interesting story.

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In this article, I arrangement on comment that inquiry for you and also giving girlfriend the background of howACP fits into modern firearms. Here"s the straightforward answer:

ACP = automatic Colt Pistol

Check out the video next if you want the fast answer and also stick approximately for the rest of the post if you want the complete scoop.

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Most the us understand this:

The invention of the automatically pistol changed the see of firearms.

But there to be a catch...

The introduction of relatively compact, slim semi-automatic pistols forced a standardization of caliber.

Here"s why:

Many revolvers forced rimmed rounds that remained seated in the cylinder after gift discharged.

However, semiautomatic pistols, such as the Colt 1911, walk not need rimmed rounds.

In fact, having a in salt that gone beyond the diameter of the cartridge would reason the round casing to record or snag.

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

Browning recognized that the Colt 1911 required a ring that would eject after gift discharged and also would load easily into a magazine.

For those that have owned or shot the pistol before, you know it take away a very details caliber of round – the .45 ACP.

This leads to the key question, which we will certainly answer next.

What walk ACP stand For?

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

inform the technician or armorerinform the customer

By tie to the round, it specified that Colt design this round particularly for your pistols.

That is clever marketing, right?

The difference needed to be made from an engineering standpoint and for the consumer.

Browning labeling these new pistol ring – such as the .32 or .45 auto – as Automatic Colt Pistol rounds. This ended up being abbreviated merely asACP.

Same Caliber, various Bullet

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

A notable instance would be the .45 Colt – otherwise known as the .45 long Colt.

The big difference in between a .45 ACP and a .45 Colt round is 10 millimeter of included length to the lengthy Colt and also a protruding rim at its base.

This do the .45 Colt ideal for revolvers. The .45 ACP round was made just for semi-automatic pistols.

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

However, many revolvers are constructed for rimmed cartridges and the ACP ring does not have actually a protruded rim.

It would certainly be dangerous to load a .45 ACP right into a .45 Colt revolver. It would certainly be terrible to fill a .45 Colt into a pistol that accepted .45 ACP.

Both rounds have various dimensions even though they room the same caliber.

The loss of size 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 big variety the firearms. It became necessary to begin referring to every caliber by a device that made sense for the company.

A few notable automatic Colt Pistol calibers include: .25, .32, .380, .38, and also .45.

All of these calibers room denoted through an “ACP” in ~ the finish of them. However, these rounds are also referred to as “auto.”

For instance, if you walk into a pistol store and ask the clerk for a situation of .32 ACP or .32 auto, he will hand girlfriend the same instance of ammunition.

There is no distinction other 보다 which mechanism a human being uses to refer to those specific rounds.

It gets amazing when we think about how this rounds fit right into the hand gun arena.

Automatic Colt Pistol Calibers

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

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

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

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

It to be the initial selection of Ian Flemming once he began writing about James Bond.

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

Speaking of underpowered—before innovations in the ar of smokeless total powder, numerous of the automatic Colt Pistol rounds were thought about to be very underpowered.

The .25 and .32 ACP room still supplied by some European police forces. The .380 Auto is very popular together a concealed bring 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 due to the fact that it was provided in the Thompson submachine gun and also the Colt 1911A1 semi-automatic pistol.

It earn its place in American nostalgia.

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The only round come no much longer be in energetic production is the .38 ACP.

The .38 ACP was an attempt to bring the caliber native the people of detective revolvers to pistols.

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

In terms of preventing power and also potential, the .38 has always been underpowered in comparison come its larger, more powerful .357 Magnum cousin.

Colt Was not the Only firm to placed Its Name right into Calibers

While we might recognize popular calibers such together the .45 ACP or .380 ACP, it is crucial to realize Colt was not the only firm to use this trick.

As stated earlier, Sig Sauer produces firearms chambered in .38 SIG. A few other notable 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)