AR piston driven vs standard direct impingement

[O.S.O.K.]

I was just reading a discussion about standard vs piston AR's on another board.... and it ocurred to me that the standard impingement design really isn't much different than having a piston... basically, you just eliminate the piston/extension of the bolt and replace it with a longer gas line - the operation is exactly the same - the gas pushes the bolt back either via the piston or directly. The only real difference is that you've removed the gas from the reciever area.

So, for the advantage of doing that - removing the gas from the receiver area, you get a shit load of extra parts, more weight and decreased accuracy in most cases.

This is the best argument against the AR piston system that I can think of.

People cite "reliability" but I have to ask if there's any evidence for this ascertion? Here again, you simple trade one possible issue with another new one (extra parts to break).

[binky59]

I heard pros and cons to each system. Inpingment, more meticulus and frequent cleaning, better accuracy overall with more
precise tolerances. Gas piston system, less precise because of lower tolerances, less cleaning required because gasses aren't
blown back directly into the receiver. Iv'e seen videos (Gunny on YouTube) that show the differences between a Colt AR and
an AKM. The colt had better shot placement on multiple shoot volleys with less barrel rise and faster aquisition staying on
target. The AKM on the other hand, had more barrel wobble and rise, therefore less time on target firing multiple rounds.
My pick: in heavy brush (jungle), AK, in the desert, mountains, AR

[Texas Soldado]

The Army did exhaustive testing just a year ago and the H-K gas piston system was considerably more reliable (Fewer failures to feed) than the standard M4.
That said, my personal experience of 27 years in the Army is that gas impingment system works just fine if you clean your weapon as it needs it. I started with an XM16E1, carried an M16A2 in Afghanistan for a year and an M4 w/203 in Iraq for a year.
*side note... I don't have positive feedback on the M9 Beretta in the sand. Trouble with magazines, follower sticking after 3-4 rounds and not feeding rounds. Had a spring break that rendered ithe trigger inoperable until I could evacuate the weapon to FOB Warrior for repair.
Keep the Beretta , I will take a trouble-free Glock anytime before the M9.

[5.56NATO]

As designed (20in bbl) and with proper ammo it worked fine. When they shortened it they got a lot of problems such as ftf, bob, and bolt breakage, along with case head rupture on extraction and extractor failures. A 20in tube suffers little of that.

[O.S.O.K.]

I thought they fixed all of that with the M4...? Wasn't that just initial problems?

[Texas Soldado]

I never had a single jam on my M4. The same M4 I trained with for 3 months at Fort Riley, KS, I deployed with. It was a great weapon. If the H-K upper works even better than I'm all for it, just push out the pins and slap it on top of the lower.
IMO, it's high time the military transitioned completely to the 6.8 SPC.
More flags... more fun...

MORE LEAD... more kinetic energy

[gpwasr10]

As designed (20in bbl) and with proper ammo it worked fine. When they shortened it they got a lot of problems such as ftf, bob, and bolt breakage, along with case head rupture on extraction and extractor failures. A 20in tube suffers little of that.

Mine's a 20", it suffers NO troubles at all. It does not even run that dirty... now my old 11.5/5.5"... Whole different story.
When I was doing research on the platform before rolling my own I found that most end users seemed to feel thatthe platform worked best as a rifle.

[old Grump]

All I know is in the Army Reserves we played in the sand a lot with the M16 and it was not my favorite weapon although I admit it was half the weight and less cumbersome to carry everywhere. It was filthy filthy filthy dirty and the only way to keep it running between cleaning was to keep it wet. Duck snot in my pocket at all times and used liberally. My hand and shirt sleeve were always black but it kept going. Never tried using it in the cold or in mucky wet places like swamps but if it got dunked in a crick or river I just poured the water out, gave it a little LSA and kept on trucking. Simple is good and the less parts to move the fewer things to break. Not having ever had my hands on a piston gun I have no way of comparing but it seems to me no matter what system lube and clean always pays dividends no matter what system. I'd almost rather run out of ammo before running out of LSA. I still had my 45 and grenades.

[mriddick]

As far as I know all the AR based piston designs have issues with wear, if you're a government who can buy and replace parts without worry about cost it's not a big deal but otherwise I'd stick to the way it was designed.

[Charliebravo]

I want a piston upper with a can.

[O.S.O.K.]

Why not just the can - why the piston too? Some advantage to the piston for a supressor?

[btcave]

I thought they fixed all of that with the M4...? Wasn't that just initial problems?

The M4's that I have shot in my career did just fine. I loved them and kept them clean. Though they never failed dirty, and I did all my weapons qualifications with a dry bolt to reduce the amount of cleaning after the range time. Simple green is your friend as long as you lube it up nicely after cleaning and don't let the little nazi supply sergeant see you using it.

I never had a fail to feed that wasn't a result of magazine feed lips being fucked.

M16 A1's or M16's were crap though. A2's and M4's were the shit.

I've never shot an AR with a piston, so I can't comment on their pluses.

[Schuetzenman]

I've got DI original type AR rifles, they are filthy pigs. I have never gotten more than 375 rounds through one without it slowing down the bolt speed from carbon build up to the point where it stopped going into battery. The forward assist could get it into battery. Spray it with WD40 and get it all juicy and they will take off and run again. But you will get black oily shit sprayed in your face when it goes off.

I built a Middy with piston system. It is oh so very clean after a session at the range. I have 600 rounds maybe thorugh it and it has never stopped running. Weight, maybe 2 grams vs. the DI gas tube. Meaning there is no tangible weight increase from a piston drive on an AR. So far I would say there is a tangible increase in reliability. Accuracy on this weapon wasn't super before conversion to piston, after conversion I don't see any significant change it how it shot.

Using a Suppressor on it is merely a matter of screwing on the Blackout Flash Hider. There is no adjustment and I don't notice any extra recoil energy. I think the piston helps bleed off any back pressure spike you might get with DI and a suppressor. Here's my piston AR and the AAC can on it. It is my go to weapon. Bring on the Zombies I'm ready!



Now suppressors do add weight and at the muzzle, so do forward grips and flash lights. Don't worry about a piston system making the weapon heavy, it doesn't.

[O.S.O.K.]

Nice rig. I'd like a can. Maybe I'll get one after the move....

[5.56NATO]

I never had a single jam on my M4. The same M4 I trained with for 3 months at Fort Riley, KS, I deployed with. It was a great weapon. If the H-K upper works even better than I'm all for it, just push out the pins and slap it on top of the lower.
IMO, it's high time the military transitioned completely to the 6.8 SPC.
More flags... more fun...

MORE LEAD... more kinetic energy

There are going to be a lot of examples like yours, but if you ask around you will hear about issues, mainly with bolt breakage and extraction issues.

[5.56NATO]

Mine's a 20", it suffers NO troubles at all. It does not even run that dirty... now my old 11.5/5.5"... Whole different story.
When I was doing research on the platform before rolling my own I found that most end users seemed to feel thatthe platform worked best as a rifle.

With a 20in tube the only thing I worry about is mags and ammo. If the ammo is tarnished or not highly polished, the more likely it is to jack up in the mag and do a bob or ftf. If the mag is fooched it's going to bob or ftf no matter if piston or whatever design. Good thing there's a zillion different mags to choose from today.

[Helen Keller]

I installed a bushmaster piston conversion in my 11.5" gun last month.

runs like a top, stays cool and clean too.

Took less than 1 minute to clean after almost 180 rounds , quick wipedown of the internals and that was it.



Still trying to burn up all that awful PMC stuff I got years ago.

[Charliebravo]

Why not just the can - why the piston too? Some advantage to the piston for a supressor?

A co-worker of mine was running a SBR'd D.I. gun with a can. Said it was filthy. He converted it to a piston and said it ran much cleaner.

[gpwasr10]

With a 20in tube the only thing I worry about is mags and ammo. If the ammo is tarnished or not highly polished, the more likely it is to jack up in the mag and do a bob or ftf. If the mag is fooched it's going to bob or ftf no matter if piston or whatever design. Good thing there's a zillion different mags to choose from today.

Yup, 20" is the way to go no doubt. I feel PLENTY gunned with mine. Plus it;s only as long as my Marlin 1894SS... people say they are long... but they are only as long as a pistol caliber lever gun... Small price to pay for the FPS and Velocity.