Can 9mm 1911 be modified to shoot .380ACP?

[jlist]

9mm is already pretty weak for full size 1911s. 380acp is even weaker. But I'm still hopeful that maybe it can work on Officer or Defender size 1911 with a lighter slide and barrel. I shot .380ACP from my Defender 9mm 1911. It shoots fine but the slide doesn't fully cycle, the case doesn't eject and won't load a new round. I wonder if it's as easy as swapping in a weaker recoil spring or cutting the recoil spring short to shoot .380ACP? Maybe also switching to weaker main spring? Does anyone have experience with this?

['ol shooter]

I would just look for a Mustang, it's already .380.

[jlist]

I would just look for a Mustang, it's already .380.

That's true. I have some .380ACP ammo. Just trying to see if there's a way to shoot them w/o adding a new gun.

[boopiejones]

This sounds like an interesting experiment. I imagine it would work just fine with a lighter recoil spring. I might buy some and try it out.

Although I don’t know why anyone would really want to do this. Recoil on a 9mm 1911 is already pretty minimal, and 380 is more expensive than 9mm so it isn’t a cost issue.

[Canucky]

9mm is already pretty weak for full size 1911s. 380acp is even weaker. But I'm still hopeful that maybe it can work on Officer or Defender size 1911 with a lighter slide and barrel. I shot .380ACP from my Defender 9mm 1911. It shoots fine but the slide doesn't fully cycle, the case doesn't eject and won't load a new round. I wonder if it's as easy as swapping in a weaker recoil spring or cutting the recoil spring short to shoot .380ACP? Maybe also switching to weaker main spring? Does anyone have experience with this?

After shooting 380 through it? Whats the cases look like?

[Joezamboni]

You could shove in a lighter recoil spring and try but consider this. The load data for 45acp and HP38 varies between 4.2 grains to 7 grains depending on the projectile. For 380acp it varies between 2.4-3.9 grain based on the projectile. That's a big difference in powder charge. I already find in a 9mm 1911 that the slide cycles slowly. Considering most 380 firearms are blowback action I wouldn't even bother trying to move that 1911 slide with it.

[plumbum]

Now I’m going to have to feed my G17 some .380 to see what happens.

[jlist]

G19 shoots .380 OK, same issue, slide doesn't cycle. It's less easy to change recoil spring weight on Glocks, though.

[jlist]

Do report back if you have results. It's a cost issue, though not ammo cost. I have some .380ACP ammo and I don't want to buy a new gun for them. It'd be nice if I can shoot them with a new spring that only costs a few bucks

[JTROKS]

If you’re really serious about building one I’m sure there’s a custom builder can take a short chambered 9mm 1911 barrel and finish ream it to 380 ACP. Making it work will need tuning the recoil spring and maybe lightening the slide a bit.

[IVC]

If you don't change your barrel, you're headspacing on the extractor and counting on it to stop the round from moving forward where it would normally headspace on the case mouth.

This is the same as firing .40 out of 10 mm Glocks (you can find plenty references online).

It works most of the time if the round is powerful enough to cycle the slide (or if you change the slide/spring setup), but like anything that is against the design of the firearm, it can have its own issues from reliability to safety.

[tommyboy1966]

After you master that you can ponder if you can get your 1911 to work with 9mm makarov.

[Monkeywrench]

IIRC most .380 were in straight blowback designs. Not saying it wouldn't work though. Browning makes a pretty sweet .380 1911 that is 85% scale.

[I Swan]

After you master that you can ponder if you can get your 1911 to work with 9mm makarov.

9mm Makarov uses a .363 bullet. Would probably need a new barrel.

[mausercat]

I used a 380 barrel from Fusion Arms in a 9mm Colt Commander and I got it to work using a 9 lb recoil spring and a 15 lb mainspring. It however only works well with American Eagle 380 acp ammo because it has a little bit more power. This conversion is being done in Mexico because any caliber more powerful than a 380 acp is prohibited over there. I did to see if I could get it to work.