[quote author=cjt50 link=topic=137.msg706#msg706 date=1283422993]
Nope, never tried it. I have not had any issues yet where I need to play with it. I would think it would decrease the amount of gas used to cycle the action, possible causing it to short stroke.
YMMV
8)
[/quote]
Concur. The XCR is the same way. Some will run all day long on "S" and others won't. I don't think it's indicative of production inconsistencies just that each rifle will behave a little different under different conditions.
I have seen a couple posts around from folks that feel their rifle is OVER gassed. Once spares become availabe they could get hold of an extra gas plug and play with the ACR's "S" gas port, increasing it step by step, to hit the sweet spot.