One of the very highly respected guys over at Sniper's Hide (Padom) is highly endorsing the RCA adjustable gas key that they make.
I haven't tried one yet, but I might..............simply change out the BC, but you do have to take the BCG out of the gun to adjust it.
RCA is a great company to deal with & everything else I've used from them has been top shelf
MM
RCA Adjustable Gas Key BCG