How many are using gas pistons?

[Darth Stang]

I recently upgraded my M4gery to a CMMG gas piston setup and I couldn't be happier. After dealing with my M-4 in Iraq and getting constant sand jams, I was dedicated to making sure my SHTF rifle would not perform similarly. Got the CMMG clamp-on kit from VegasArms on gunbroker and it came in pretty solid (minus the adjustment wrench). Had a significant amount of trouble lining it up with my garage tools, and managed to scratch the locking nut quite badly. Eventually took it to Pete at Evil Black Rifles (my class III dealer) and he got it all lined up for me. Now I know I have a rifle that pretty much won't jam even after being in the mud and hardly gets dirty after a day at the range. i even stick my finger in the chamber after a dozen rounds and it's cool to the touch. LOVE IT!!!

I was wondering if anyone else has changed or is pondering. I highly recommend--get AK reliability with AR range and accuracy!

[BPTactical]

Well not to throw a blanket over the parade but Eugene Stoner was a might smarter than people give him credit for. He came up with a great gas impingment system for operating a weapon.
That being said I can understand it's shortcomings but I don't feel the piston is the ideal fix.
The rifle was not designed for a piston system so when one goes about trying to re-invent the wheel some problems become apparent. Number one offender is "bolt tilt". With the GI system the gas impulse forces are evenly distributed in the BCG so you get a smooth push on the bolt carrier that is focused on the centerline of the action. The BCG travels rearward in a linear movement.
With the piston system all of the "impulse" is focused on what used to be the gas key, on top of the bolt carrier. This causes the rear of the carrier to tilt downward, sometimes leading to functionality issues and accelerated wear to the buffer tube and in extreme cases I have seen it begin to wear into the buffer tube almost to the point of wearing through.. Bolt tilt is also hard on the upper receiver, it imparts forces to it in a way it was not designed to take and can accelerate wear as well.
The piston system also adds weight to the front end and you have increased the amount of reciprocating components. Anytime parts move they are subject to failure. Any time mechanical complexity is increased so does failure potential.
Parts left off cost nothing and cannot fail.
The piston system is also detrimental to accuracy. Gone forever is the concept of a true "floating" barrel. Also think about this: what do you think is happening to the rifle when the piston and pushrod are moving rearward at a high rate of speed? The barrel is flexing more than with a GI system and the recoil is slightly sharper, both are detrimental to accuracy potential.
With the piston system the instant the round passes the gas port you have mechanical movement before the round leaves the barrel whereas on the GI system the bolt carrier does not start appreciable movement until the round has left the barrel.

The piston has its merits but again I don't feel it is the ideal fix for the few shortcomings of the GI system.
This is just my observations and opinion of the piston system.
Your mileage may vary.

[Hoser]

Too many issues with piston guns right now. I will wait 10-15 years before trying them.

[Great-Kazoo]

i'm running an adams arms unit on a sbr. runs fine no issues easy installation etc. Like it with my halo unit too. I have an AK106 i really like especially suppressed!. I scored the AA kit for a smoking deal NIB and went for it. Are there issues, depending on the mfg early vs. late production and customer service. If i could get one for the wife's lw bbl i would.

Are they a must have item? not really. Could i have spent the money some where else? sure. However with all the shit i see folks hang off of everything incl a HiPoint Carbine, i said F$%^& IT. YMMV

[ray1970]

Well not to throw a blanket over the parade but Eugene Stoner was a might smarter than people give him credit for. He came up with a great gas impingment system for operating a weapon.

+1 on this. Never had a problem with any of mine when properly maintained.

[BushMasterBoy]

When Stoner designed the weapon, the main market was the Vietnam theater of operations. Think wet steamy jungle, not hot sandy desert. I went with both types of systems. Each one has its' pros & cons. Gas impingement with less parts or piston that runs cooler. If gas impingement, then expect weapon failure under extreme rapid fire as proved in Afghanistan. If you go piston then expect to have to clean the piston system regularly to maintain reliability.

CMMG is pretty good system. Won't work with 22LR adaptor. Nice part of CMMG is you can adjust gas piston to work a noise suppressor more efficiently.
Not sure what brand Special Forces is using today, but I'm sure most prefer the reliabilty of not over heating the weapon over gas impingement. Gas piston system makes the weapon feel nose heavy.

It would be interesting to see thermal imaging of two almost identical weapons of both type systems to see what is happening thermodynamically.

[BPTactical]

It would be interesting to see thermal imaging of two almost identical weapons of both type systems to see what is happening thermodynamically.

Yes it would. If IIRC there was a film clip somewhere of piston and GI side by side with Beta Mags.
The GI rifles tube was cherry red and the rifle stopped running while the piston was warm but touchable and running.

[SA Friday]

Not sure what brand Special Forces is using today, but I'm sure most prefer the reliabilty of not over heating the weapon over gas impingement.

Depends on the unit. Last I heard, the 416s were the flavor of the moment in SOC. Green Berets and Rangers were still running DI, but had a lot of latitude.

Everything gets too hot in the desert. A color other than black or dark green is more important than overheating due to lack of controlling the rate of fire IMO.

I've shot both and still prefer DI over the piston. desert sand never jammed any of my firearms while in Iraq. You just have go use oil that's viscous enough to not be absorbed into the metals from he perpetual exposure to high heat, and clean and clean and clean. I ran over 2k round through my M4 in one day while in Souther Iraq during a training day. Lots of exposure to the environment that day and hot as hell too. Guns with the CLP failed. the guns with motor oil just kept on shooting.

[Darth Stang]

Awesome replies, though it seems many are not fans of the piston system yet. My main reason fro going gas piston was the failure experience with the sandy desert. I've put 2-300 rounds through the system and so far I've been impressed. The chamber stays cool and clean, and I've had not feed failures. I agree with BP Tactical that the accuracy has been affected, I will need to experiment with different brands to find one that will do consistent groups at 100m. I have an Aimpoint Comp M2 identical to my USGI rifle and I've managed to dial it in to where I'm confident of hitting man-sized targets at 300m, but not head shots.

Eugene Stoner made a great rifle, and I'm just trying to improve on mine!

[Great-Kazoo]

Awesome replies, though it seems many are not fans of the piston system yet. My main reason fro going gas piston was the failure experience with the sandy desert. I've put 2-300 rounds through the system and so far I've been impressed. The chamber stays cool and clean, and I've had not feed failures. I agree with BP Tactical that the accuracy has been affected, I will need to experiment with different brands to find one that will do consistent groups at 100m. I have an Aimpoint Comp M2 identical to my USGI rifle and I've managed to dial it in to where I'm confident of hitting man-sized targets at 300m, but not head shots.

Eugene Stoner made a great rifle, and I'm just trying to improve on mine!

Depending on twist rate across the board 55gr ball has proven to be (for me) the most consistent grouping wise. PMC, FED, Privi, LC, SA, and WOLF have been where i want them to be. No matter what gas unit, AA, Sig 556P and the Arsenal 106, most 1:7 and a few 1:9. YMMV