1911 caliber conversion adapter/insert

**Aguila Blanca** · November 3, 2019, 07:40 PM

A friend from Europe sent me an e-mail in which he mentioned the notion of converting a 1911 to shoot .380 ACP. I know that Imbel in Brazil makes a 1911-ish model that shoots .380 ACP, but it's a fixed barrel pistol, and it's not available in the U.S.

My friend and I exchanged a flurry of e-mails, discussing the possibility of making a chamber adapter to convert a 9mm or .38 Super barrel to 9mm. This couldn't be a drop-in caliber converter, we were talking about boring out the original chamber and inserting an insert with the .380 ACP chamber in it. One of the questions we were wrestling with in how thick to make the wall of the new chamber insert, and how much of the original chamber to leave? Conceptually, I fired up AutoCAD and sent him a sketch showing the wall thickness as 50:50 -- the thickness of the insert chamber equal to the remaining thickness of the original barrel.

Is that a good ratio, or should they be different thicknesses? I can think of two possibilities:

The insert is machined using a short length of cut-off 9mm barrel as the "raw material." In this case, the insert would be hardened, ordnance-grade steel.
The insert is made from a piece of mild steel rod or bar stock. This would be easier to machine, but would not be as strong.

For the first, my inclination would be to keep the wall thicknesses equal. For the mild steel option, I was thinking that maybe it should be 1/3 for the insert and 2/3 for the outer, original chamber area.

Any thoughts or suggestions? For companies that use two-piece barrels, such as Springfield Armory, what do they do? Are they 50:50?

Jim Watson · November 3, 2019, 11:01 PM

George C. Nonte liked 50:50 for barrel reline.

But the FIRST thing to do is to find out if a .380 will function the action.

I studied a 9mm Makarov conversion back when there was some ammo available with heavier bullets than usual. I loaded some 9mm P down to Mak power factor and was able to get the gun to work. But the supply of heavy ball dried up before I got to bending metal so I didn't pursue it.

TRX · November 4, 2019, 12:21 AM

I've kept an eye on .380 conversions for a while. The only one I know of who claimed he got the gun running is here: https://forums.1911forum.com/showthread.php?t=358389

It sounds like a Bubba job, though.

Any 1911 barrel maker who has a .380 reamer on hand should be able to do a proper barrel. You can order an unchambered barrel and do it yourself as long as the hood is relieved to clear the reamer.

You would need a 9mm or .38 Super slide; preferably not one of the wide 9mm/.40 slides.

9mm extractor for the 9mm slide.

Light recoil and main springs.

Long 9mm ejector.

Large-radius firing pin stop.

9mm slide stop if you want the slide to lock back.

9mm magazines, preferably ones with a filler piece that doesn't let the shorter-than-.45 9mm cartridges slap back and forth. Some 9mm mags don't have that, but the .380 is shorter yet; no need to borrow trouble until you get the rest running.

.45 and 9mm frames are *supposed* to be cut differently at the feed ramp; in practice, many manufacturers don't seem to worry about it.

I'm pretty confident you could make a full-size 1911 reliably cycle .380 ACP, considering Hi Point makes a .380 with a slide a lot bulkier than a 1911...

MTT TL · November 4, 2019, 02:55 AM

Theoretically you could should practically any caliber less powerful than 45 ACP with a complete upper swap so long as the mag will fit in the well. That is how I shoot 22lr. I must say I enjoy it just as much as shooting 45ACP, although for different reasons.

November 3, 2019, 07:40 PM	#1
Aguila Blanca Staff Join Date: September 25, 2008 Location: CONUS Posts: 18,459	1911 caliber conversion adapter/insert A friend from Europe sent me an e-mail in which he mentioned the notion of converting a 1911 to shoot .380 ACP. I know that Imbel in Brazil makes a 1911-ish model that shoots .380 ACP, but it's a fixed barrel pistol, and it's not available in the U.S. My friend and I exchanged a flurry of e-mails, discussing the possibility of making a chamber adapter to convert a 9mm or .38 Super barrel to 9mm. This couldn't be a drop-in caliber converter, we were talking about boring out the original chamber and inserting an insert with the .380 ACP chamber in it. One of the questions we were wrestling with in how thick to make the wall of the new chamber insert, and how much of the original chamber to leave? Conceptually, I fired up AutoCAD and sent him a sketch showing the wall thickness as 50:50 -- the thickness of the insert chamber equal to the remaining thickness of the original barrel. Is that a good ratio, or should they be different thicknesses? I can think of two possibilities: The insert is machined using a short length of cut-off 9mm barrel as the "raw material." In this case, the insert would be hardened, ordnance-grade steel. The insert is made from a piece of mild steel rod or bar stock. This would be easier to machine, but would not be as strong. For the first, my inclination would be to keep the wall thicknesses equal. For the mild steel option, I was thinking that maybe it should be 1/3 for the insert and 2/3 for the outer, original chamber area. Any thoughts or suggestions? For companies that use two-piece barrels, such as Springfield Armory, what do they do? Are they 50:50? __________________ NRA Life Member / Certified Instructor NRA Chief RSO / CMP RSO 1911 Certified Armorer Jeepaholic

November 4, 2019, 02:55 AM	#4
MTT TL Senior Member Join Date: October 21, 2009 Location: Quadling Country Posts: 2,780	Theoretically you could should practically any caliber less powerful than 45 ACP with a complete upper swap so long as the mag will fit in the well. That is how I shoot 22lr. I must say I enjoy it just as much as shooting 45ACP, although for different reasons. __________________ Thus a man should endeavor to reach this high place of courage with all his heart, and, so trying, never be backward in war.

November 3, 2019, 11:01 PM	#2
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,535	George C. Nonte liked 50:50 for barrel reline. But the FIRST thing to do is to find out if a .380 will function the action. I studied a 9mm Makarov conversion back when there was some ammo available with heavier bullets than usual. I loaded some 9mm P down to Mak power factor and was able to get the gun to work. But the supply of heavy ball dried up before I got to bending metal so I didn't pursue it.

November 4, 2019, 12:21 AM	#3
TRX Senior Member Join Date: September 24, 2008 Location: central Arkansas Posts: 400	I've kept an eye on .380 conversions for a while. The only one I know of who claimed he got the gun running is here: https://forums.1911forum.com/showthread.php?t=358389 It sounds like a Bubba job, though. Any 1911 barrel maker who has a .380 reamer on hand should be able to do a proper barrel. You can order an unchambered barrel and do it yourself as long as the hood is relieved to clear the reamer. You would need a 9mm or .38 Super slide; preferably not one of the wide 9mm/.40 slides. 9mm extractor for the 9mm slide. Light recoil and main springs. Long 9mm ejector. Large-radius firing pin stop. 9mm slide stop if you want the slide to lock back. 9mm magazines, preferably ones with a filler piece that doesn't let the shorter-than-.45 9mm cartridges slap back and forth. Some 9mm mags don't have that, but the .380 is shorter yet; no need to borrow trouble until you get the rest running. .45 and 9mm frames are supposed to be cut differently at the feed ramp; in practice, many manufacturers don't seem to worry about it. I'm pretty confident you could make a full-size 1911 reliably cycle .380 ACP, considering Hi Point makes a .380 with a slide a lot bulkier than a 1911...