Shot sting velocities will give you a clue. If you have a bell curve, then probably no reg. If you have a pretty straight shot string, probably so. If you want 100% definitive Yes/No, you'll have to do some dismantling. The risk with dismantling is that you risk damaging a few o-rings. It will be behind part "G" if you have one. There is a sequence to taking it apart properly. Tom
You can tell by the small 2mm breather hole that is drilled just behind the air gauge for the regulator........ visible when you take it out of the stock....