Which AR piston driven 308

[osteodoc08]

Long story short, my Sig 716 was "stolen" and I won't be getting it back soon (or at all) I am looking for a replacement. I have a POF 415 and have been very happy with it. I'm looking for that level of quality in a 308. Anyone have suggestions or feedback on any specific models? I have local dealers for POF, LWRC, Sig, Larue, etc.

[Artful]

Why AR? - check out SCAR17

[osteodoc08]

Why AR? - check out SCAR17


Familiarity and I already have a Sig716.......that'll hopefully find its way back to me soon. I may just pick up another as I was pretty happy with it.

The Scar17 is pretty awesome though. Proprietary mags suck though ($$$$)

[Artful]

http://www.mosesmag.com/product/moses-mag-scar-h-20/
Moses Mag SCAR-H 20$27.99

[Petrol & Powder]

I won't belittle the AR platform and when you use a piston to eliminate the direct impingement gas system you correct the most serious shortcoming of that system, but.........there are some other very good .308 semi auto rifles out there.

Despite it's old technology, the M14/M1A platform is still an awesome rifle. I'll never part with mine.

The H&K G3 [H&K 91] has always been one of my favorites but real G3's are prohibitively expensive now. The G3 is frequently underrated and I've shot some excellent examples of that rifle. They are far tougher and accurate than most people know.

The FAL and the Springfield knock off SAR-48 are decent rifles and my old SAR-48 would hold it's own against any AR-10. Unfortunately that design is a bit heavy for its class.

Just throwing that out there.

[popper]

And your objection to the full gas system is? There is a genIII (?) system with new lug/bolt design that is supposed to be really good.

[osteodoc08]

No objection to gas at all actually. I've just had really good luck with my piston driven AR platforms. My POF415 and Sig716 have both been flawless through a few thousand rounds each.

[Petrol & Powder]

And your objection to the full gas system is? There is a genIII (?) system with new lug/bolt design that is supposed to be really good.

Direct gas impingement has worked for over 50 years and I think it is easily capable of functioning when needed under normal conditions given even a modicum of maintenance, however I do think it is a weak link in the AR platform.

Direct gas impingement (placing the gas cylinder on top of the bolt carrier within the receiver) allows for fewer moving parts and a lighter over-all system but it also introduces hot/dirty gas into the receiver. It's not a question of, "can it work"; it clearly works. It is a question of, "is the weight savings and simplicity worth the cost of the extra heat/dirt"?
No matter how you configure a direct impingement system the problems remain the same. I'm not saying the problems are significant, they clearly are not. However, most other designs place the piston and its related heat/dirt away from the action. That increases the overall weight and complexity of the system but overall reliability and durability improve with that weight and complexity.

It is not really a question of which system works,.... they both work. It is a question of which system works better and there's not a huge margin between the two. I think the piston systems are overall a bit more reliable but the direct gas system is reliable enough and generally lighter.

[popper]

Gas pistin IS the BCG, not on top - just a method to get the gas into the cylinder. Garand was an op rod gun and very reliable for gov. issue ammo. BruceB did a lot of work on other loads. Saw a video of an AK op rod doing it's dance, can't add any accuracy that way. Not trying to argue either but calculating mean-time-between-failure numbers, quantity of parts is big factor - towards failure.

[DaveInFloweryBranchGA]

AR308's are heavy rifles generally speaking and need to be to soften the recoil of the cartridge a bit in full house loads. That said, I've never seen a need in a civilian owned AR of any caliber where I felt one needed a piston set up in an AR. Keep it clean, lube it with an appropriate lube and it gets the job done. If I'm going to spend money on a piston setup on a battle rifle, I'm going to get one of the rifles designed from the ground up as a piston operated firearm. And all of that said, every gas impingement AR I've ever owned has been very accurate and reliable. And if memory serves, slightly more accurate than the piston driven versions. Which I'm reasonably sure is why, when the government tested some purpose built AR's for designated marksman/sniping purposes, they went gas impingement.

[dkf]

If you want a piston system I would take a hard look at PWS. Like the MK216.

[Petrol & Powder]

Gas pistin IS the BCG, not on top - just a method to get the gas into the cylinder. Garand was an op rod gun and very reliable for gov. issue ammo. BruceB did a lot of work on other loads. Saw a video of an AK op rod doing it's dance, can't add any accuracy that way. Not trying to argue either but calculating mean-time-between-failure numbers, quantity of parts is big factor - towards failure.

I'll disagree in part and agree in part.

In a direct impingement system the end of the gas tube becomes the "piston" but it doesn't move. The hollow gas key that fits over the end of the gas tube becomes the "cylinder" but it does move with the bolt carrier. It accomplishes the same thing as a moving piston and fixed cylinder; it just reverses the relationship of what we normally call a piston.

I agree that, given some maintenance, a direct impingement system can be very reliable. It is certainly lighter and simpler.
I've never liked the introduction of hot/dirty gases into the receiver but I don't think that it is a total deal breaker.

As for the large gas piston on an AK style rifle screwing up the barrel dynamics; you'll get no argument from me about that but there are about 100 other things that also screw up the accuracy (or lack of it) in the AK system. The AK was made to function, not to win rifle matches.

[garym1a2]

For me the advantage of the Gas piston gun is not the piston but the op-rod/charge handle difference. When my AR's go down as they will if you shoot a lot, they can be either easy to clear or near impossible. With an oversized case from bad ammo/my reloads at times I had to pry open the bolt with a screw drive. Other times use the Motar approach. With my AK74 SGL104 I had a stuck case once, pulling by hand would not unlock the bolt. But a simple hit the handle on a wall clears it. So would have a boot to the handle.

[osteodoc08]

I've used the mortar approach with good success. I now put all my reloads through a case gauge and catch out of spec reloads.

As a side note, my 716 was returned to me, but I'd still like another 308. I'm looking hard at the Sig DMR

[popper]

I now put all my reloads through a case gauge and catch out of spec reloads. We learn fast don't we - most of the time. I did look at the POF several years ago, decided on DI - I think $$ decided for me.
P&P, if the 'gas key' were the piston, no need for gas to enter the BCG, just let it flow into the receiver.