AR automatic rifle?

[KYmorris]

If I were to get a class 3 AR lower and mate to a heavy barreled upper (16.5- 18 in) wouldn't this be quite useful with surefire quad mags as a light support arm?

[Pokeguyjai]

You'd probably want to go for a LWRC M6A3 piston upper IMO.

[CoryT]

Without an open bolt conversion and a QC barrel, you'll find it overheats in short order. 90 rounds of full auto will heat the system to the point of cookoff. Even going to a piston system, the bullets will be melting in the barrel, leading to very poor performance. The M16 platform in .223 is not well suited to continous full auto fire.

[OdieWon]

Ya, it sounds like something fun to play with. But what NFA item DOESN'T?

Unless you actually had a small unit training group and regiment, and an AO that it could be put to use in at the very least in an emergency.

But if you've got the cash laying around, dude, do it. There simply isn't a better way to burn $100 bills than to smoke a bunch of ammo in just a few seconds.

That's not to say that I don't really dig FA fire, I do. But I don't have enough experience with it to make use of the few bucks I have for training and gear.

[Pokeguyjai]

Without an open bolt conversion and a QC barrel, you'll find it overheats in short order. 90 rounds of full auto will heat the system to the point of cookoff. Even going to a piston system, the bullets will be melting in the barrel, leading to very poor performance. The M16 platform in .223 is not well suited to continous full auto fire.

If he has a class 3 lower already and wants to do a SAW type gun, the AR is not a bad bet as long as he understands the limits of the system. 90 rounds sounds about right for cooking off in an DI AR, but that is A LOT of ammo in a very short amount of time. The piston along with the CHF barrel will help keep his gun cooler but won't make a huge difference. So the main issue is the shooter seeing the limit and controlling his ROF.

IMO the piston system will give him the best upper for the buck, and he will see the benefit of a piston (a properly developed/tested/manufactured one at that) with an AR used in this role.

[oef24]

I have had the opportunity to test a full auto piston AR and do multiple drum dumps. I put three 150 round drums through the gun as fast as I could reload it and only 3 trigger pulls. At no time did any part of the system get red or white hot and no cookoffs. All ammo was SS109 and I think that the piston system plaid an important part in keeping the system cooler than a DI gun.

O

[eaboecke]

If you got money to burn look at at full auto lower on a Barrett REC7 in 5.56. IMHO the best piston upper for the AR platform. You would end up with something like the Marines are playing with right now. The Infantry Automatic Rifle (IAR), basically a heavy barrel HK 416.

In my professional opinion, belt fed is needed for the AR/SAW role at the team level.

[Spiffy]

If he has a class 3 lower already and wants to do a SAW type gun, the AR is not a bad bet as long as he understands the limits of the system. 90 rounds sounds about right for cooking off in an DI AR, but that is A LOT of ammo in a very short amount of time. The piston along with the CHF barrel will help keep his gun cooler but won't make a huge difference. So the main issue is the shooter seeing the limit and controlling his ROF.

IMO the piston system will give him the best upper for the buck, and he will see the benefit of a piston (a properly developed/tested/manufactured one at that) with an AR used in this role.

And this is why we have burst trigger settings. A mechanical fix for a training issue.

[Coolhand77]

I've always wondered why the equivalent of aluminum heat sinks hasn't been tried with the "MG" type ARs. If you could pull heat away from the barrel [aluminum is good for this] and use the piston instead of DI to reduce return gas induced heating, then nickle boron the reciever internals, that might improve the auto rifle capabilites.
Heh, figure out a way to power it thermally and you could even add some small fans to help cool the barrel heat sinks [think PC processor heat sink/fan combination]

One of the few reasons I want a class three lower...so I can experiment with stuff like this.

[EDELWEISS]

A M16-RPK isnt a bad idea if your heavy into ARs. Its been tried before by Colt during the early SAW trials. I think the Canadians also made one too. Given that a FA M16 lower more likely to be available than a M249 its more "do-able". Even in semi it has some good features as part of a team concept. A heavy barrel with some sort of heat dispersion is a good idea too. Plus assuming you have the FA lower, uppers arent THAT expensive if you burn out the barrel.