380 AR

[CapnMac]

32 acp would be fun too

To my thinking, it would really "want" more of a AR-18 design, and need to be a braced pistol or SBR with a 10-12" barrel, what with 32acp not gaining that much out of a longer barrel.

Now, the other direction that could be fun in an AR platform would be one of the 9x23s. Naturally, that points more at 38super+P rather than 9Browning long or the like. Magazine compatibility would be the sticking point to my thinking.

But, in fairness, I also thought that Marlin was short-sighted in not offering the Camp Carbine in 38super. (Would have needed a better buffer pad and a stout spring, but, still . . . )

 

[Archibald Stanton]

To my thinking, it would really "want" more of a AR-18 design, and need to be a braced pistol or SBR with a 10-12" barrel, what with 32acp not gaining that much out of a longer barrel.

Now, the other direction that could be fun in an AR platform would be one of the 9x23s. Naturally, that points more at 38super+P rather than 9Browning long or the like. Magazine compatibility would be the sticking point to my thinking.

But, in fairness, I also thought that Marlin was short-sighted in not offering the Camp Carbine in 38super. (Would have needed a better buffer pad and a stout spring, but, still . . . )

That would be interesting for sure. I like the 32 auto round in conjunction with 32 magnum

 

[berettaprofessor]

If one were loading a 9mm to 380 power levels, using HP38 or CFEPistol and a 95 or 100 grain projectile perhaps, what would the charge be? Hodgdon's website gives 5.1-5.5 grains of HP38 (COL1.050) for a 100 grain FMJ, but projected FPS is 1218-1252 and that makes it 329 Ft-lbs minimum....380 commercial loads are more in the 180-200 ftlbs level.

 

[P Flados]

If one were loading a 9mm to 380 power levels, using HP38 or CFEPistol and a 95 or 100 grain projectile perhaps, what would the charge be? Hodgdon's website gives 5.1-5.5 grains of HP38 (COL1.050) for a 100 grain FMJ, but projected FPS is 1218-1252 and that makes it 329 Ft-lbs minimum....380 commercial loads are more in the 180-200 ftlbs level.

Using Quickload, a 380 maxes out around 1030 fps for a 100 gr from a 3.5" barrel using HP 38. In a 9mm case with a 1.105" AOL you get to the 1030 fps mark with 4.5 grs and pressure around half of the SAAMI rating.

Since I am just making holes in paper, I am happy with my 2.7 gr of Promo under a 108 cast bullet that does close to 820 fps from a 3.5" 9mm. With powder supplies like they are, I like knowing that using only 2.7 gr will delay the depletion of my stash.

 

[berettaprofessor]

Using Quickload, a 380 maxes out around 1030 fps for a 100 gr from a 3.5" barrel using HP 38. In a 9mm case with a 1.105" AOL you get to the 1030 fps mark with 4.5 grs and pressure around half of the SAAMI rating.

Since I am just making holes in paper, I am happy with my 2.7 gr of Promo under a 108 cast bullet that does close to 820 fps from a 3.5" 9mm. With powder supplies like they are, I like knowing that using only 2.7 gr will delay the depletion of my stash.

Perfect. Thanks.

 

[zaitcev]

I am welcome to any and all ideas on the best way to go about building an AR in 380 acp.
...
i would assume the bcg would need to be different and the barrel would need a different twist. Maybe 1:10?

I'm pretty sure that a generic AR9 bolt will work. It has the weight in the back held by a roll pin, which can be easily removed. Or, alternatively, change the buffer weight.

The most important choice is the magazine. The more or less realistic choices are:
- Glock 42 - maximum capacity 12 with ETS magazines
- MAC-11 - 32 rounds, no bolt hold-open
- The Czechpoint repro vz.61 in 380, plastic stick mags
- Beretta 84 - maximum capacity 13
- B&T TP380 - not yet available on the U.S. market
- SIG P365-380
- Roll your own, could be based on Menendez, or perhaps on Sterling (because of the round spring).

Performance-wise, I think Czechpoint Scorpion magazine is the best: it has a good capacity and supports LRBHO through the rear, which makes it far more reliable in an AR. However, its availability is in question.

Pistol magazines of B84, G42, and P365 are about the same in performance. All are easily available.

If I were making this project, I would start with G42 and perhaps switch to B&T if it's a good success. However, keep in mind that the feed path in an AR9 with Glock magazines already barely supports the 9mm Luger cartridge. I am afraid you're going to face an unsupported jump if you keep the same feed geometry. It's possible that nothing short of a bespoke magazine is going to work.

 

[Archibald Stanton]

She is complete. I’ve gone through a box so far and no jams, no misfeeds, no nothing bad. This is perfection. Went with a standard AR15 lower and the endomag conversion kit insert for 9 mm in the magazine. Had to go with a 1.7 oz buffer and reduced power spring. Working perfectly with 380 so far. I’ll work on paper next and see how it goes.

 

[berettaprofessor]

Details please Archibald! What barrel? Using a 9 mm or a 223 bolt?

I have a 9mm 223 pistol, and endomags. I know that originally people were talking about a 9 mm bolt, but a 380 ACP and 223 use the same #4 lee case holder, wouldn't the 223 fit the case head? You telling me I just need a light buffer and spring?

 

[jmorris]

Using a 9 mm or a 223 bolt?

I would guess he is using the 9mm blowback bolt but it would be more impressive if he had a gas operated .380, using a .223 bolt.

 

[Archibald Stanton]

Details please Archibald! What barrel? Using a 9 mm or a 223 bolt?

I have a 9mm 223 pistol, and endomags. I know that originally people were talking about a 9 mm bolt, but a 380 ACP and 223 use the same #4 lee case holder, wouldn't the 223 fit the case head? You telling me I just need a light buffer and spring?

380 barrel with a 1:10 and a 380 bcg. I have a 9mm bolt but it’s not quite the same

 

[berettaprofessor]

Where did you end up buying them?

 

[Archibald Stanton]

Where did you end up buying them?

Armory dynamics

 

[12Bravo20]

Very interesting and I bet the recoil is pretty mild. I didn't even know anyone was making 380 bolts and barrels.

 

[Archibald Stanton]

Very interesting and I bet the recoil is pretty mild. I didn't even know anyone was making 380 bolts and barrels.

I have never seen them have them in stock before and I haven’t looked for a long time. I thought they stopped making them until they emailed me. I was on their waiting list forever. I have a 9 mm bolt I can use and you can get any custom barrel made although it is a pain if the company is not already set up for them. They will definitely charge you for it

 

[berettaprofessor]

Not bad prices eh? About $360 for a barrel and BCG. I take it although they call it a "glock upper compatible bcg", you don't have to use it with a glock style lower.

 

[Archibald Stanton]

Not bad prices eh? About $360 for a barrel and BCG. I take it although they call it a "glock upper compatible bcg", you don't have to use it with a glock style lower.

I used a standard aero ar15 lower but you have to use the endomag insert if you do. You also have to remove the LRBHO bar from the upper if it has one for glock but it’s easy to do

 

[WestKentucky]

Not too crazy. I want to do a 32acp ar which would be a little bit tougher but not much. Use a 300Blk barrel set back and rechambered. Blowback setup with a deferent bolt face.

I am curious though, why choose .380? Just love for the round?

 

[Archibald Stanton]

Not too crazy. I want to do a 32acp ar which would be a little bit tougher but not much. Use a 300Blk barrel set back and rechambered. Blowback setup with a deferent bolt face.

I am curious though, why choose .380? Just love for the round?

Because I could only find where one other guy had ever done it and he did it as a rifle. I am sure many other people have done it but they don’t talk about it online if they did lol. I do enjoy the round for plinking and targets, really low recoil, low noise. No pain on this old body