I have shot an M-16 with one of the old SIONICS (Mitch Werbell) suppressors. While it did away with muzzle blast, you could still hear the crack of the bullet going over 1300 fps. Doing away with muzzle blast/flash, and minimizing recoil (not an issue w/ M-16) are the only two advantages that I can see to using one on a high powered rifle.