My Weekend Project

[dave2176]

Not current on any .308 based cartridges. What's out there?

I know a .243 is the same cartridge as a .308, just necked down. What Rick said made me wonder about the .45 ACP. The base of the .45 cartridge is .005" larger diameter on the ammo I have but it still appears to fit the bolt okay. Rick, is the AR10 .308 bolt compatible with the .45 ACP? This is interesting, keep it going.

Dave

 

[wrmiller]

The .45 acp is a pretty low pressure round that doesn't launch a bullet very far. And .223 or .243 doesn't interest me. I'm more of a larger bore type, in that nothing below 30 cal does much me. My two favorite pistol/revolver cartridges are 10mm mag and .44 mag. A carbine length AR chambered in those might be interesting. Is a .444 marlin a rimless cartridge? Good stopping power for shorter ranges.

 

[wrat]

I know this is kind of silly to ask as you already have shown you like them but, what do you think about shooting the "pistol" ARs? I've considered making a couple but I just can't get my heart around the "Why?" They seem a bit cumbersome/large for a pistol and not much smaller than a carbine.

What are your guys' take on it?

Well, beinz you asked all nice-like
Obviously, to each his own and while i like anything with a Rebel Flag (these days more than ever) there's a few reasons that come to mind.

1. You're right, it's a big pistol. So maybe "pistol", while the legal term, isn't especially the best description. Making it work like a Glock or 1911 is never gonna happen. What will work is making it work like a subgun. And a subgun is way up on the fun list, IMO; even in semi-auto. About the smallest it's ever gonna get is an oversized Mauser or "Han Solo gun".

2. As a subgun, it works well in a shoulder or whippit rig. That's a terrific amount of firepower in an easily concealable package. We have Constitutional Carry, here yet shockingly few dead bodies piled in the streets. So carrying such a rig is perfectly legal, here.

3. Caliber selection is wide and readily changeable. .223 in an 8" barrel is no big treat and makes for a cumbersome one-hand rig, like you might suspect. But it 's fun in a two-handed subgun. If a guy wants, changing over to 9mm or .45 is simple and quick. Further, .300AAC is basically a pistol round when loaded subsonic, which is also useful. A big draw is the 5.7FN round like the Secret Service now carries (not AR). The upper is cool, the mags are sizeable, and the empties drop out the mag well. Sure, any of these can be had in a carbine, but in a smaller subgun format, they're also useful.

4. With the "wrist brace" - a popular piece of plastic - it's still a pistol, though it transitions well to the shoulder. All very legal. So in that respect, you actually have the best of both worlds in a short barrel format. You're not stuck with a 16" barrel minimum.

5. Barrel can be virtually any length from 16" down to just an inch or two for the blowback bolt configs. So "smaller than a carbine" is easily achievable when that matters.

5. There's no other .45/9mm you can put together as cheaply and expect it to shoot for 5,000 rounds. No other .300AAC or .223 handgun hardly exists at any price.

That's all i can think of off the top of my head.

Time for Santa Claus here, soon.

Wrat

 

[wrat]

The .45 acp is a pretty low pressure round that doesn't launch a bullet very far.

The .45 ACP is best suited for an AR15 action not the larger and heavier AR10.

My two favorite pistol/revolver cartridges are 10mm mag and .44 mag. A carbine length AR chambered in those might be interesting.

Both of those are actually fairly common, though most do the gunsmithing themselves. Somewhat easier than .44mag would be .44 Automag, which is, essentially, .44mag in rimless format using cut-down .308 cases. This is also good in an AR15 package because the pressures are low enough. Take an ordinary 7.62X39 AR bolt and open it up a few thousandths to accept the .308 head.

Is a .444 marlin a rimless cartridge? Good stopping power for shorter ranges.

No. The .444 Marlin is a rimmed cartridge. Good thumper, though. Because of the pressures and longer throw, you'd need the larger, heavier AR10 action.

Rimmed cartridges can be made to work just fine in semi-auto. It takes a lot more gunsmithing and magazine work, but there are lots of rimmed semi-auto setups out there. The Desert Eagle comes to mind and it was designed around what is basically an AR bolt.

However, a guy could make ".444Marlin Rimless" out of .30-06 cases holding a .44mag pill. That's a bit of barrel/chamber work, but nothing all that tough, machining-wise. Interesting wildcat that i'm absolutely certain has already been done many times.


Wrat

 

[Rick Leslie]

Merry Christmas everyone! Late night tonight. I'll try to address all that's happened in the thread.

45 ACP as well as most rimless pistol rounds adapt quite nicely to the AR15 format. They can be made to run in DI (gas, locked breech) or blow back. Each has advantages and disadvantages but the DI wins in my book. Very handy and fun but the practical is a little limited. Main advantage is mag interchangeability with your pistol.

The AR10 is readily adaptable to almost any caliber with the short case length (51mm roughly) and the .470 to .475 inch case head. This includes .243, .260, 7mm-08, and .358 for starters. Then there's the wildcats. There's a really neat cartridge made from a cut down -06 case and loaded with .44 cal bullets. A rimless 444 so to speak. Uses 444 dies and load data. There's also the 22-250, 257 Roberts, 7 x 57, etc.

As for the wrist brace: I believe it's been determined by ATF that if you shoulder it you change the intent and create an SBR. Illegal without the proper stamp. Check the ATF website to be sure. I would play it safe and not do it.

I know a .243 is the same cartridge as a .308, just necked down. What Rick said made me wonder about the .45 ACP. The base of the .45 cartridge is .005" larger diameter on the ammo I have but it still appears to fit the bolt okay. Rick, is the AR10 .308 bolt compatible with the .45 ACP? This is interesting, keep it going.

Dave

Theoretically it would work, but the AR10 is much too large for the 45 ACP. It's a much better fit in the AR15. Even then the gas system has to be very short and the port opened up a bit, as well as the bolt face and extractor work. But a well tuned AR45 is a ton of fun to shoot. I've got one running, one pistol in the works and 2 rifles in the works. One for me and one for my wife.

 

[wrmiller]

Hmmm... I'm kinda liking the idea of a AR10 based .444. Short range brush gun that packs a punch. May have to investigate this a bit more. Starts with a -06 case? Being more of a private pistolsmith my knowledge of long guns is relatively new. I'll have to get a few cases and start measuring. Thanks.

 

[wrat]

I know you probably got it, already, but just trying to make sure something i said doesn't come out wrong.

The .444 Marlin does not start with a .30-06 case. It's its own case -- and it has a rim. Here's a nice writeup on it

But IF a guy wanted to make an AR10 with a really nice thumper round, then IMO the .444 Marlin would the place to start. I would, however, *switch* from the rimmed Marlin case to a .30-06 case for simplicity of mags and feeding.

To those just tuning in, because of the inherent confusion in gun designation, the .444Marlin is not really .444 diameter. The same way a .44Mag is not really .44 diameter. They're both .429 diameter and can, somewhat interchangeably, shoot the same projectiles.

I also think a .444 is a far superior choice to the currently popular .458SOCOM the military uses in an A15 platform. Better yet, using .30-06 cutoffs and .429 bullets, it's way, WAY less costly to load, compared to .458. And, of course, on an AR10 platform, much bigger loads can be used.

Having an AR10 in .444Marlin starts with getting a .429 barrel made. About $275 from Pac-Nor. Then you do the machining to make it AR-ready. Lesser men in a hurry might hire this out. But hobby machinists will work this no matter how long it takes. How do I know? I'm smack in the middle of exactly such a project.

Wrat

 

[wrat]

As for the wrist brace: I believe it's been determined by ATF that if you shoulder it you change the intent and create an SBR. Illegal without the proper stamp. Check the ATF website to be sure. I would play it safe and not do it.

As long as the brace is kept in original config -- that is, not even taking the little velcro strap off -- then you can shoot it any way you like. Off your shoulder; off your forehead; off your knee; whatever a guy likes.
Legal is legal.
I mean, not tying to play internet lawyer, here, but yes, this is well-plowed ground.

Wrat

 

[wrmiller]

I know you probably got it, already, but just trying to make sure something i said doesn't come out wrong.

The .444 Marlin does not start with a .30-06 case. It's its own case -- and it has a rim. Here's a nice writeup on it

But IF a guy wanted to make an AR10 with a really nice thumper round, then IMO the .444 Marlin would the place to start. I would, however, *switch* from the rimmed Marlin case to a .30-06 case for simplicity of mags and feeding.

To those just tuning in, because of the inherent confusion in gun designation, the .444Marlin is not really .444 diameter. The same way a .44Mag is not really .44 diameter. They're both .429 diameter and can, somewhat interchangeably, shoot the same projectiles.

I also think a .444 is a far superior choice to the currently popular .458SOCOM the military uses in an A15 platform. Better yet, using .30-06 cutoffs and .429 bullets, it's way, WAY less costly to load, compared to .458. And, of course, on an AR10 platform, much bigger loads can be used.

Having an AR10 in .444Marlin starts with getting a .429 barrel made. About $275 from Pac-Nor. Then you do the machining to make it AR-ready. Lesser men in a hurry might hire this out. But hobby machinists will work this no matter how long it takes. How do I know? I'm smack in the middle of exactly such a project.

Wrat

It's OK Wrat, I got it. But I DO understand the caution. Especially on a forum.

Not sure I'd even want to attempt to get a rimmed case like the .444 Marlin to strip/feed out of a magazine. I had enough troubles getting .38 super (semi-rimmed cartridge) to reliably feed in my competition guns. Now there's the 9x23 which negates that issue. I simply meant that I would use the -06 case for an AR10 based .444.

And I too am not impressed with the .458 SOCOM. The .444 could be a much better overall round IMO. And a big thanks for the Pac-Nor mention. Already bookmarked.

I'm just finishing up some modifications to my bench mill, so I will soon be turning to my next project which will be a STI based 2011 in .40 S&W. I may have to add another AR10 to the list...

 

[Rick Leslie]

There is a thread somewhere here: http://www.weaponsguild.com/forum/index.php

I've searched and searched but can't find it. It explores the possibility of the 444 Rimless. The 06 case size works with the 444 Marlin dies. You would have to have a custom reamer ground or grind one yourself, and the case would headspace on the case mouth like most straight walled rimless cartridges. It would follow the same principle as this round: http://www.weaponsguild.com/forum/index.php?topic=28383.0

I personally like the 357 AR on the AR15 chassis better as a quick handling brush gun, but the 444 would be the same on the AR10.

We may need to start a new thread for these AR wildcat builds so we don't muddy this thread.