Thanks for all of the input. My loads are not subsonic. I already have the low mass carrier and captured spring. I picked them up cheap and thought I would try them. If they dont work then no harm done. I will just sell them. What about bolt bounce. I have never experienced it that I know of. With the increased forward speed of the bolt and not having the extra weight on the carrier to you run an increased risk of the bolt bouncing out of battery?