The collapsible stock problem can be addressed by placing the upward angled rail like portion of the moveable part on the rear bag and controlling the fine adjustments by squeezing the bag. Avoiding the adjusting release is essential. The recoil of the 556 or other AR15 round makes things easilly controlled. I have a nylon bag on a front rest that is able to slide and use this with the cheese graters. You have to check its position after each shot. AR10s are a bit different but I dont have any adjustable stocks on my AR10s. I think you can prevail by good follow through and repositioning bags after each shot .Not the best system but you can still shoot good groups. And as was mentioned before follow through is really necessary. Follow through is just the act of doing the same thing before, during and after trigger squeeze.
