 When fired, the force of the gases expanding inside the baffles of the suppressor act to force the suppressor body forward in relation to the barrel.The spring allows the barrel to recoil while the suppressor stays in place; the pressure of the gases between the two components helps force them apart as well, much like the VIckers-type boosters described above.Many suppressor boosters incorporate an indexing system which allows the suppressor to be reoriented in a number of different rotational positions, allowing the end user to fine-tune the weapon's point of aim.