MOD please delete this thread. I've found answers in this thread:

http://www.ar15.com/archive/topic.html?b=6&f=20&t=375872

Correct me if I'm wrong, but since gas piston AR's vent gas in the handguard, running a suppressor that would typically cause blowback in a direct impingement AR would not be a problem in the case of a gas piston driven rifle, right?

Wrong. There is still plenty of blowback. I'm running a PWS and SIG516 suppressed and the inside of the receiver is filthy. Piston operation does not eliminate this because fouling is still coming back through the bore/chamber. Gas to face may not be quite as bad, but it's still there.

So would you recommend saving up for an OSS suppressor instead of going with a traditional suppressor in this case? (elimination of blowback and minimization of heat mirage)

Honestly, its really not that bad. The OSS suppressor hasn't been around long enough to say good or bad. I went with the Saker 5.56 and it's great.

its just the nature of the beast and something you deal with. suppressors make for dirty chambers and magazines.

my best advice is to get a small yet efficient can like the AAC Mini4 or one of those SF SOCOM 556 MINI. they will have reduced back pressure since they are shorter. of course they are louder but its a super sonic rifle cartridge, whattya expect?

i have an old AAC SRAC -SD can that is about 1.5" shorter than the M4 2000 can and it runs a tad cleaner and its way more handy on any rifle.