+1, if your rifle is working fine un-suppressed, then the additional back pressure is what needs to be tamed.  


H2 is what you need for reliable functioning in full auto.  Going heavier is just more reciprocating mass.  May help to bandaid the problem but heavy buffers don't reduce the excess fouling from too much gas.  I've got plenty of buffers and used to play the buffers game but now just do all tuning in the upper and leave my lower configuration the same.



Below is a high speed video of the same 10.5" M16 being fired in full auto running LC M855 one with regulated gas and the other non-regulated.  Both running H2 buffers and standard power springs.




Another video demonstration of the 10.5" suppressed in real time.




Let me know if I can be of any assistance.



Plenty more info, videos and pics on my site:  http://micromoa.com
 

Good article discussing this with the late John Noveske here: http://www.defensereview.com/noveske-rifleworks-n4-light-recce-carbine-john-noveske-interview-part-one/





I personally prefer the standard gas system which really is a piston if you read Stoner's patent.


I've tried several 'pistons' out there and have broken carriers and bent oprods doing a lot of heavy full auto.


'Most' are also louder than a standard gas system.

 

+1, just gas it right and you'll be fine.  Likewise, I use an H2 buffer for all my upper configurations except for blowback stuff like 9mm or LM7.  All tuning is done in the upper for all gas operated calibers.



micromoa.com