Gas rings lining up do not matter. I've tried it with no issues and have read where others have tried it with no issues too. I read from a few people that they were told during a Colt Armorers course it didn't really matter. Hell, they're going to rotate anyway.
My guess - either you didn't put something back together right, did you completely disassemble the bolt? Check you extractor and it's spring and insert, fatter side of spring does toward extractor. If they're ok maybe you need a O-ring around it. I'm assuming it's a carbine and they can have extraction issues with rifle springs and inserts. - OR more likely Stag does not stake their carrier keys correctly. Check to see if the screws are tight, I forgot the # in-lb, and restake. A leak here will cause short strokes.
I don't know about a properly built AR being finicky. My two Bushmasters, one 20" and one 16", as well as two friends of mine's Bushies will eat anything and everything. They're bone stock internally; and yes that is using Wolf, Academy Monarch (both steel and brass), XM193, Q3131, Q3131A, MK262, .223 Win white box (any kind), Rem UMC, Radway Green, etc.