Thoughts on Piston System For Precision Upper...

[Deepwoods]

Ok, its not a precision upper per se, but...

I had a mid-length Superlative Arms piston kit not being used, and put it on a 13.7" Centurion Arms Recce barreled upper. Before I pin the muzzle (a HUXWRX FH), I thought I would ask the brain trust.

Reasons to use it: I had it, it's adjustable, there's a bit less gas (I shoot lefty), its different...
Reasons not to use it: the web says piston systems aren't ideal for accuracy, and that the piston itself can introduce some inconsistencies, its not as simple as DI... the whole cleaner than DI thing isn't black and white

The barrel is shortish and thickish and probably (?) less prone to piston induced movements (a phrase I just made up). Im about 100 rounds in with a high magnification scope and getting a bit over 1 moa off a rest, 77 gr IMI. I am pretty rusty so I'm a factor.

Eventually, the upper will get a 1-8, so tiny groups probably isn't in the cards. But for the sake of the quest, and the theory of piston...

Thoughts?

 

[3rdfocal]

I have a piston AR15 that is exceptionally accurate. And they run 100x cleaner than DI guns. After having a piston rifle, the cleanliness factor has made me somewhat despise DI guns. If you're getting a little over 1 moa and you're gonna run a 1-8... I'd say you're set and any accuracy you think you maybe could be losing is a non factor anyways.

 

[Deepwoods]

Appreciate the input.

I spend more time than I should pondering the non-factors... the what ifs.

I have a 10.5 upper with the SA piston kit that I like, and this mid-length used to be on a 16"; I do like them.

 

[BuildingConceptsllc]

I just sent my side charging lefty , piston upper to Paul Craddock to have a 16" Bartlein with CLE chamber done and installed. It's going to be awesome! I much prefer running a piston and I have no issues with accuracy. Do it

 

[danr]

Not ideal for accuracy…..
Love those SA piston kits. Here’s a pic of what my 20” 6 arc and 20” 556 (top and middle) will do compared to my DI 22” 6 arc. And the only reason the 22” doesn’t have one is SA doesn’t make a .875 piston kit. I know they’re only 3 rd groups but these are to check zero as I’d rather use up my ammo hitting steel than punching paper these days

 

[schmi015]

Shoot it!

 

[Deepwoods]

Not ideal for accuracy…..
Love those SA piston kits. Here’s a pic of what my 20” 6 arc and 20” 556 (top and middle) will do compared to my DI 22” 6 arc. And the only reason the 22” doesn’t have one is SA doesn’t make a .875 piston kit. I know they’re only 3 rd groups but these are to check zero as I’d rather use up my ammo hitting steel than punching paper these days
View attachment 8302846

Not a terrible argument...

As to the "shoot it" admonishment... yes. The bout of windy, mid 30s weather forced me to huddle by the gun safe, and that just encouraged the "what if..."

 

[supercorndogs]

After having a piston rifle. I wouldn't choose one even if it cost the same as building a DI rifle. Mine absolutely did not run cleaner than a DI rifle. Brass was consistently cover in black soot worse than anything else I have ever shot. And it was noticeably louder suppressed than other rifles. I feel like the piston made it exract cases earlier than a DI due to less gas volume reaching the piston faster than it would reach the bolt.

 

[tucaz]

After having a piston rifle. I wouldn't choose one even if it cost the same as building a DI rifle. Mine absolutely did run cleaner than a DI rifle. Brass was consistently cover in black soot worse than anything else I have ever shot. And it was noticeably louder suppressed than other rifles. I feel like the piston made it exract cases earlier than a DI due to less gas volume reaching the piston faster than it would reach the bolt.

brass from the piston upper was covered in black soot?

 

[supercorndogs]

brass from the piston upper was covered in black soot?

Edited post to say my piston "did not" run cleaner than a DI rifle.

 

[tucaz]

Edited post to say my piston "did not" run cleaner than a DI rifle.

so when running suppressed right?

thats what i came the conclusion of, pistons and DI get pretty sooty when suppressed with all the blow back. that's why i don tuse cans on piston stuff. why bother? DI's get dirty anyway so they are my can'ed up rifles.

 

[Deepwoods]

For my purposes, I have OSS cans, so there's less blow back when suppressed anyway. Going off memory... From the dozen or two rounds I put through this piston + suppressor, the brass was dirtier than unsuppressed, but not as dirty as when I used my Surefire cans.

When not suppressed, even a bit less gas coming back can be a benefit bc my my face is on the same side as the ejection port.

I do appreciate hearing others experiences...

 

[supercorndogs]

so when running suppressed right?

thats what i came the conclusion of, pistons and DI get pretty sooty when suppressed with all the blow back. that's why i don tuse cans on suppressed stuff. why bother? DI's get dirty anyway so they are my can'ed up rifles.

Every kind of gun gets dirtier when shooting suppressed. But my piston ar was way worse. I think from unlocking and extracting early. I assume the chamber pop is what made it seem louder. The only stuff I have even seen come remotely close to spit out brass so dirty has been 6.5 Grendel and 6 ARC. Mine was an Adam's arms. The two settings for suppressed and un-suppressed worked well.

What do you mean you don't use cans on suppressed stuff?

 

[db2000]

Every kind of gun gets dirtier when shooting suppressed. But my piston ar was way worse. I think from unlocking and extracting early. I assume the chamber pop is what made it seem louder. The only stuff I have even seen come remotely close to spit out brass so dirty has been 6.5 Grendel and 6 ARC. Mine was an Adam's arms. The two settings for suppressed and un-suppressed worked well.

What do you mean you don't use cans on suppressed stuff?

I think he meant piston stuff

 

[DeathBeforeDismount]

I don't know why people always try and reinvent the wheel and have to learn the hard way. Precision ARs and semi auto platforms have designed tested and redesigned for the last 40+ years and there is one constant. DI systems are superior and inherently more accurate. All of the high precision ars.... are DI. Jp, kac, MWS, GAP, seekins, ect. A company like LMT who makes pistol ars...doesn't even fuck with them in their precision rifles.....this is what we call a hint. KAC who has probally spent more in R&D in the AR platform than all other companies combined...still runs a gas system. Ect ect ect.

The 417 is the anomaly and it still ain't shit compared to a dialed in DI gun.

The piston/ar debate was settled almost 20 years ago. Unless you need to:
Run a short barrel
Run predominately suppressed
Heavy firing schedule/full auto
Have to be able to run a variety of different pressure ammo.


Then a DI gun will always be superior.

 

[tucaz]

Every kind of gun gets dirtier when shooting suppressed. But my piston ar was way worse. I think from unlocking and extracting early. I assume the chamber pop is what made it seem louder. The only stuff I have even seen come remotely close to spit out brass so dirty has been 6.5 Grendel and 6 ARC. Mine was an Adam's arms. The two settings for suppressed and un-suppressed worked well.

What do you mean you don't use cans on suppressed stuff?

miss spoke. meant i dont use cans on piston stuff, it all gets dirty

and i should add i’m a lefty so its easy to build DI uppers in left side ejection

to help OP out, i have 2 LWRC uppers scoped. an old 18” M6A3 DMR that shoots about 1-1.5 MOA with razor core and AAC 77gr OTM, depending on me.

the other is a new IC A5 16”. it will do the same.

they are both a little over gassed and its harder to stay in the scope to see the shot but i did modify the piston cups by drilling extra holes to vent more gas early. it helped.

 

[schmi015]

miss spoke. meant i dont use cans on piston stuff, it all gets dirty

and i should add i’m a lefty so its easy to build DI uppers in left side ejection

to help OP out, i have 2 LWRC uppers scoped. an old 18” M6A3 DMR that shoots about 1-1.5 MOA with razor core and AAC 77gr OTM, depending on me.

the other is a new IC A5 16”. it will do the same.

they are both a little over gassed and its harder to stay in the scope to see the shot but i did modify the piston cups by drilling extra holes to vent more gas early. it helped.

Try the Hornady Frontier 75 grain in your M6A3. Mine loves it. 4x acog and hitting a silhouette at 600yds is a piece of cake. Let me know how it shoots for you. I love the 4 position gas block on the A3's.

 

[Deepwoods]

To the comment about reinventing the wheel... I totally get it. I spend more time than necessary with the "why be different when "normal" is proven" vs the "different is fun sometimes just bc its different, and maybe it doesn't matter enough in this case."

Ive got other, more precision oriented uppers--both longer and shorter-- that are DI and not over complicated.

Currently, I have the piston's gas block adjusted in SA's recommended starting point (fully open), and haven't adjusted to minimize recoil or anything. Still, it *very* consistently put the brass at ~4:00 in pile a few feet off the bench no bigger than 2 hands. I thought that was pretty impressive.

 

[Crews]

Who cares how dirty the brass gets? Weren’t we talking about accuracy? Geez.