ACP (or Ack-pee) Ammo Sizes

[aaaaa]

I got to wondering what sizes ACP (Automatic Colt Pistol) ammo comes in. A Wikipedia page gives the following:

.25 ACP (.25 Auto Colt Pistol, 6.35mm Browning, .25/6.35mm Auto, 6.35×16mmSR)

7.62×17 mm Type 64 (7.62 mm Chinese) [rimless .32 ACP]

.32 ACP (.32 Auto Colt Pistol, 7.65mm Browning, .32/7.65mm Auto, 7.65×17mmSR)

.380 ACP (9×17mm, .380 Auto, 9mm Kurz/Browning Short)

.38 ACP (.38 Auto, 9×23 mmSR)

.45 ACP (.45 Automatic/Auto Colt Pistol, 11.43×23 mm)

.45 Wildey Magnum (using .45 ACP bullet)

Those in bold I am familiar with. The rest seem to be rather obscure. Odd thing is .380 ACP. Why was it not simply named .38 ACP? I guess because there must have already been a .38 ACP as listed, though they don't tell when these were developed. That .38 ACP is longer than a 9mm too.

FYI: I got that Ack-pee from a You Tube video.

 

[JTQ]

.38 ACP evolved into the .38 Super which is probably why you hadn't heard of it.

https://en.wikipedia.org/wiki/.38_Super

 

[CapnMac]

What @JTQ said.
.38acp was meant as a gallery round (as in indoors or mostly indoors) target ammo.

There were a ton of other "38" rounds out about that same time, which probably influenced the choice to call the 9x17 "380."

38acp dates to right at 1900, for the Colt auto of 1900.
Now, Georg Luger started invented the 9x19 in 1901.
JMB gave us the semi-rimmed 9x17 in 1908, and none of that System Internacionale notation for him .
The 38super dates to about 1925 and was influenced by all the 9mm largo pistols from Spain. And was a handy option for use in a 1911 where 45acp was banned got civilian use as a "military" round.

Technically an "acp" if obscurely so is JMB's 9mm Browning Long, a 9x20sr that withered on the vine as not being a 9x19 nor a 9x23

 

[fxvr5]

.38acp was meant as a gallery round (as in indoors or mostly indoors) target ammo.

Sorry. That's dead wrong.
https://en.wikipedia.org/wiki/.38_ACP

The 38super dates to about 1925 and was influenced by all the 9mm largo pistols from Spain. And was a handy option for use in a 1911 where 45acp was banned got civilian use as a "military" round.

Wrong again. Colt introduced the "Super 38 Auto" pistol in 1929. It was chambered in the 38 Automatic. Around 1933 Remington increased the speed for the bullet, pushing a 130 grain bullet at 1,300 fps, and at some point people started calling it the 38 Super.

https://web.archive.org/web/20170716064320/http://www.38super.net/Pages/History.html

And see:

Sheldon, Douglas G. 1997. Colt's Super .38, The Production History From 1929 Through 1971. Quick Vend, Inc. Willernie, MN.

 

[12Bravo20]

.38 ACP evolved into the .38 Super which is probably why you hadn't heard of it.

https://en.wikipedia.org/wiki/.38_Super

And when you go to buy reloading dies for 38 Super, the dies will be listed as 38 ACP and also stamped that way too. Or at least Lee dies are that way.

A little side knowledge. The 38 ACP reloading dies also work for reloading 9mm Largo.

AS far as why 380 ACP is called that, we Americans couldn't have any cartridge marked in their metric designations back in the day. Most of the world calls 380ACP by its metric designation of 9x17.

 

[wcwhitey]

The Colt 38 ACP first appeared in the Colt 1900. It was the biggest round that JMB could make work in a straight blowback pistol. Later it transformed into the .38 Super. The 9MM Largo is the same as the .38 ACP, just a different way of saying it.
https://en.wikipedia.org/wiki/.38_ACP

A side note: JMB gave up on the .38 ACP development partially because it was apparent that the desired military contracts would only be considered in a .45 Cartridge after the problems with the .38 Ling Colt in the Philippines. Pocket pistols and civilian designes were different though and we got .38 Super and .380 ACP.

 

[12Bravo20]

The 9MM Largo is the same as the .38 ACP, just a different way of saying it.

They are definitely different in most dimensions.

38 ACP
Base diameter 0.384"
Rim diameter 0.406"
OAL case length. 0.900"

9mm Largo
Base diameter 0.390"
Rim diameter 0.392"
OAL case length. 0.910"

While you can use either 9x19 or 38 ACP dies to reload 9mm Largo, one can run into issues trying to run 9mm Largo in a 1911 where the extractor is tuned for 38 ACP/38 Super since both have a bigger rim than 9mm Largo.

One note on 9mm Largo brass. All of the Starline 9mm Largo brass I have bought is all 0.900" in length. Since buying a 38 Super barrel for my 9x19 mm 1911, I have been using mostly Starline 9mm Largo brass since I didn't have to mess with tuning the extractor. Sometimes when an extractor is tuned for the larger rim of 38 ACP/Super, it will sometimes not reliably extract 9x19 cases. And the reason for me doing this is the fact that I already had a bunch of Starline 9mm Largo brass for my Star Model A Super.

 

[wcwhitey]

They are definitely different in most dimensions.

38 ACP
Base diameter 0.384"
Rim diameter 0.406"
OAL case length. 0.900"

9mm Largo
Base diameter 0.390"
Rim diameter 0.392"
OAL case length. 0.910"

While you can use either 9x19 or 38 ACP dies to reload 9mm Largo, one can run into issues trying to run 9mm Largo in a 1911 where the extractor is tuned for 38 ACP/38 Super since both have a bigger rim than 9mm Largo.

One note on 9mm Largo brass. All of the Starline 9mm Largo brass I have bought is all 0.900" in length. Since buying a 38 Super barrel for my 9x19 mm 1911, I have been using mostly Starline 9mm Largo brass since I didn't have to mess with tuning the extractor. Sometimes when an extractor is tuned for the larger rim of 38 ACP/Super, it will sometimes not reliably extract 9x19 cases. And the reason for me doing this is the fact that I already had a bunch of Starline 9mm Largo brass for my Star Model A Super.

Was very common to use .38 ACP in older Largo imported guns. Worked fine. Neither was easy to get but the Largo was almost impossible. I have to find the reference but as I understand it Largo was a copy of the JMB round. I see the measurement differences though. Good point.

 

[12Bravo20]

Was very common to use .38 ACP in older Largo imported guns. Worked fine. Neither was easy to get but the Largo was almost impossible. I have to find the reference but as I understand it Largo was a copy of the JMB round. I see the measurement differences though. Good point

And another very important thing to remember is that there is still some hot 9mm Largo ammo out there that was loaded for use in the Star Destroyer Carbine ONLY. One definitely does NOT want to shoot the Destroyer 9mm Largo in a 9mm pistol.

But yes you can use either one in a 1911 chambered for 38 ACP/Super. At worse you might have to tune the extractor for 9mm Largo brass.

 

[wcwhitey]

And another very important thing to remember is that there is still some hot 9mm Largo ammo out there that was loaded for use in the Star Destroyer Carbine ONLY. One definitely does NOT want to shoot the Destroyer 9mm Largo in a 9mm pistol.

But yes you can use either one in a 1911 chambered for 38 ACP/Super. At worse you might have to tune the extractor for 9mm Largo brass.

Astra surplus pistols were everywhere in the 80’s for pennies. There was a Star auto that was chambered for the Largo if memory serves. Cheap because ammo was unobtainable at the time. The trick was to buy up any .38 ACP you could find at the gun shows.

 

[fxvr5]

The Colt 38 ACP first appeared in the Colt 1900. It was the biggest round that JMB could make work in a straight blowback pistol. Later it transformed into the .38 Super. The 9MM Largo is the same as the .38 ACP, just a different way of saying it.
https://en.wikipedia.org/wiki/.38_ACP

In addition to some of the dimensional differences previously noted, the 9mm Largo is a tapered case. The 38 ACP/Super is cylindrical. The 9mm Steyr is dimensionally closer to the 38 ACP/Super.

 

[wcwhitey]

In addition to some of the dimensional differences previously noted, the 9mm Largo is a tapered case. The 38 ACP/Super is cylindrical. The 9mm Steyr is dimensionally closer to the 38 ACP/Super.

He was asking about the ACP round, answered. A Largo discussion is another matter.

 

[12Bravo20]

There was a Star auto that was chambered for the Largo if memory serves

Yes Star made their Model A and Model A Super both chambered in 9mm Largo. Which is really the only difference between the Star Model B and Model B Super being chambered in 9x19.

In addition to some of the dimensional differences previously noted, the 9mm Largo is a tapered case. The 38 ACP/Super is cylindrical

While this is true. You won't find reloading dies specifically made for the 9mm Largo. 38 ACP dies work just fine for 9mm Largo and I have never had any feeding or extraction issues in my Star Model A Super using 38 ACP die to reload 9mm Largo.

 

[fxvr5]

And another very important thing to remember is that there is still some hot 9mm Largo ammo out there that was loaded for use in the Star Destroyer Carbine ONLY. One definitely does NOT want to shoot the Destroyer 9mm Largo in a 9mm pistol.

But yes you can use either one in a 1911 chambered for 38 ACP/Super. At worse you might have to tune the extractor for 9mm Largo brass.

The Largo might not fit in some 38 ACP/Super chambers because the Largo head (.390") is much wider than the 38 ACP/Super (.384").

https://en.wikipedia.org/wiki/9×23mm_Largo

 

[wcwhitey]

Yes Star made their Model A and Model A Super both chambered in 9mm Largo. Which is really the only difference between the Star Model B and Model B Super being chambered in 9x19.

While this is true. You won't find reloading dies specifically made for the 9mm Largo. 38 ACP dies work just fine for 9mm Largo and I have never had any feeding or extraction issues in my Star Model A Super using 38 ACP die to reload 9mm Largo.

Missing the point I think. It evolved from the 1896 work of JMB as did many, many other rounds in Europe from his work. Yes they are not identical, legally could not be but close enough to steal his invention. All his cartridge inventions have copies adopted by just about every country in Europe of not directly from Colt or FN. More of a historical statement then a technical one.

 

[Jim Watson]

Let me try. Working from memory, so correct as required.

.25 ACP 1908 was 6.35mm FN 1906
.32 ACP 1903 was 7.65mm FN 1899
.380 ACP 1908 became 9mm Browning Short FN 1910

.38 ACP 1900, no direct European connection, but there are Spanish guns marked 9mm/.38 meaning 9mm Largo or .38 ACP.
.45 ACP 1905, Army adopted in 1911 with heavier bullet.

There was what might have been a .41 ACP, prototypes circa 1903-04 but Colt could see that the Old Indian Fighters and the New Moro Fighters were determined to get their .45s back and went on up.

The corresponding funny furrin 9mms may have been inspired by .38 ACP or they may have just been a case of convergent evolution.

Introduced shortly after 9mmP, probably developed concurrently but independently, FN had the 9mm Browning Long, a semi-rimmed 9x20 vs ACP 9x23SR. Not many takers, but I like it; the big FN 1903 is only a little less powerful than the Luger and a lot less complicated and expensive. Webley and La Francais made a few to their own designs.

9mm Largo is the Spanish adoption of the 9mm Bergman Bayard, a 9x23 rimless tapered case.
9mm Steyr is their house design, a 9x23 rimless straight case.

Straight, tapered, semi-rim, rimless; there is a lot of tolerance overlap and interoperability like some (but not all) Largos accepting, even marked for .38, or using Super dies to load Largo ammo, or as seen on another board, using Largo brass to load Steyrs.

Starline makes some specialty versions, the .38 Super Comp which is .38 Super rimless, and .38 TJ which is also a .38 Super rimless but with a huge extractor groove so that there will not be any full diameter brass not entering a resizing die.

It was the biggest round that JMB could make work in a straight blowback pistol.

You are going to have to 'splain that one. There might be a drawing or even a model of a Browning designed blowback .38 but Colt sure didn't make them. I recall a gas operated design and a rotating barrel that would likely have been made in .38 if chosen for production.

 

[wcwhitey]

Let me try. Working from memory, so correct as required.

.25 ACP 1908 was 6.35mm FN 1906
.32 ACP 1903 was 7.65mm FN 1899
.380 ACP 1908 became 9mm Browning Short FN 1910

.38 ACP 1900, no direct European connection, but there are Spanish guns marked 9mm/.38 meaning 9mm Largo or .38 ACP.
.45 ACP 1905, Army adopted in 1911 with heavier bullet.

There was what might have been a .41 ACP, prototypes circa 1903-04 but Colt could see that the Old Indian Fighters and the New Moro Fighters were determined to get their .45s back and went on up.

The corresponding funny furrin 9mms may have been inspired by .38 ACP or they may have just been a case of convergent evolution.

Introduced shortly after 9mmP, probably developed concurrently but independently, FN had the 9mm Browning Long, a semi-rimmed 9x20 vs ACP 9x23SR. Not many takers, but I like it; the big FN 1903 is only a little less powerful than the Luger and a lot less complicated and expensive. Webley and La Francais made a few to their own designs.

9mm Largo is the Spanish adoption of the 9mm Bergman Bayard, a 9x23 rimless tapered case.
9mm Steyr is their house design, a 9x23 rimless straight case.

Straight, tapered, semi-rim, rimless; there is a lot of tolerance overlap and interoperability like some (but not all) Largos accepting, even marked for .38, or using Super dies to load Largo ammo, or as seen on another board, using Largo brass to load Steyrs.

Starline makes some specialty versions, the .38 Super Comp which is .38 Super rimless, and .38 TJ which is also a .38 Super rimless but with a huge extractor groove so that there will not be any full diameter brass not entering a resizing die.



You are going to have to 'splain that one. There might be a drawing or even a model of a Browning designed blowback .38 but Colt sure didn't make them. I recall a gas operated design and a rotating barrel that would likely have been made in .38 if chosen for production.

Poorly written on my part @Jim Watson. It was too big of a round for his blowback design and what lead to the need for his short recoil locked breech design of the 1900. All in the pursuit of a true military pistol. What evolved into the 1911. 9mm Browning Long in the FN1903 and 380 ACP in the FN19010 was the biggest round possible for the blowback. Although some countries were content with the .32 ACP.

 

[herrwalther]

The 380ACP got its name by measuring the exterior diameter of the loaded cartridge (.379) instead of the bullet size (.355). The 38 ACP is named after the neck diameter at roughly .385. The 38 ACP is a direct parent to 38 Super and a step parent of sorts to 380ACP.

https://www.firearmsnews.com/editorial/is-the-380-auto-obsolete/452476

 

[doubleh]

"FYI: I got that Ack-pee from a You Tube video."

I would have let it remain there. Youtubers, sheesh.

 

[12Bravo20]

The Largo might not fit in some 38 ACP/Super chambers because the Largo head (.390") is much wider than the 38 ACP/Super (.384")

While this is true for factory ammo made. it is not true for all of us that reload 9mm Largo since the only choices in reloading dies are 38 ACP dies or some have even use 9x19 dies.

 

[Vern Humphrey]

. Odd thing is .380 ACP. Why was it not simply named .38 ACP? I guess because there must have already been a .38 ACP as listed.

Correct. The .38 ACP predates the .380 ACP.

 

[Jim Watson]

The 38 ACP is ... a step parent of sorts to 380ACP.

There is really little if any connection, they have no dimension in common, unlike .38 ACP and 9mm BL.

If you were particular, you could get .32 SAP - Savage Automatic Pistol - ammo for the pistol recommended by Bat Masterson. Companies are reluctant to put competitors' names on their products; like .38 Colt Special and .30-30.

Smith and Wesson got really weird with the .35 S&W.

 

[gwpercle]

When it comes to the naming and nominclature of American handgun rounds there is very little rhyme or reason to how they are named ... one of the most confusing subjects you can study .
Arms makers naming the same round different names simply for advertising and selling reasons .
The only thing I do know is when you see the offical name of a cartridge like 45 ACP it's for Automatic Colt Pistol and was developed for Colt . A lot of rounds are mistakenly labled ACP but in truth the real name is simply Auto ... but the naming waters are so muddy I can't honestly cite wich is what .
When I started reloading (1967) I had to buy a book " Cartridges of the World" to try and keep it all straight ... I buy a new edition ever few years to try and keep up ... but it's still a most confusing subject .
Gary

 

[Jim Watson]

Well, you can't fit ".38 Rimless Smokeless" on a headstamp.

 

[Speedo66]

.380 ACP (9×17mm, .380 Auto, 9mm Kurz/Browning Short)

Also 9mm Corto to our Italian friends.