A firearm suppressor with a recoil booster may be provided. In one example, the suppressor may include a housing, a back end member coupled to the housing, and a recoil booster coupled to the back end member. The recoil booster may be configured to couple to a firearm. The recoil booster may include a coil spring, a rear cap coupled to the back end member, and a piston configured to slide relative to the rear cap. The rear cap may include a main body at least partially disposed within the back end member and including a first bearing surface to receive a first end of the spring and a flange extending forward from the main body and maintained within an inner circumference of the spring. The piston may include a second bearing surface configured to receive a second end of the spring. Additional embodiments and related methods are provided.