I have Mack and PTG, as well as factory upgraded/modified 700 bolts. The Mack is the nicest of the bunch. It took a little fitting, but its at about 500rds now and working smoothly. The point where it met the top of the action in the rear gave a little hitch on closure. That whole area must be a little advanced for extraction timing to suit any 700 era, but I only noticed the hitch at the closure contact point. Polished some squared edges, and it was off to the races. They even modified their pineapple grenade knob for me and sent it with it on (I asked by email and they said no prob). While the whole package won't rival a good custom action, its the overall best I've tried so far on a 700 receiver body.