Considering a piston AR, possible to get subs and supers functioning ?

[este]

I'm debating whether or not simply having an adjustable gas head is going to cut it. I have not made any determination on port size on the barrel yet.

With a heavy contour 10" barrel I plan to put the gas block at 1.5" to 3" before the muzzle, and always shoot with the suppressor. I don't care if it won't cycle with the suppressor, actually I would prefer it.

I have no doubt supers will function. I'm just curious if 208, 220, and 240gr subs will eject, load a new round, and lock back on empty.


Does anyone have any experience with piston semis? I know Frank did a 552 but it sounded to me like anything lighter than 240s wouldn't work 100%.

[Alleycat]

I use a SSK three position gas block. It works with everything. Some one should be able to set you up with something similar. I have heard the gas system on the Sig makes it a bit loud when used with a suppressor due to the way it vents gas. There is a thread on Silencer Talk that deals with piston system of the Sig. I believe most of the piston ARs vent into the handguard. You will probably get a nice little pop from that area. Now if you could get the adjustable gas block from the piston system and adapt it to the DI system I would be all over it.

[Stealth-X]

I believe the Adam's Arms piston conversion is adjustable (low, high and off for super, subs, and single shot) and it has a good reputation.

HK 416 was 1.5 db louder when suppressed than a DI AR
LMT MRP piston was 1 db louder than a DI AR. Measured at the shooters ear.

Regards,
Nate

[THE DOCTOR]

I tried using an ares piston conversion on subs with the 300 whisper and a lot of different powders and bullet weights and couldn't get it to run subsonic supersonic was no problem but that defeats the purpose of this round. My gas port is in the carbine position so I have another couple barrels ordered to try it with the port in another position.

Two things that made my gun run more reliably was a heavy buffer and welding one port closed on the carrier.