A bolt carrier may be provided. The bolt carrier may comprise a counter-bore, a housing, a cap, and a free-floating mass. The counter-bore may be disposed in the bolt carrier. The housing may be disposed in the counter-bore. The housing may have an interior, a first end, and a second end. The cap may be disposed at the second end of the housing and may be connected to the bolt carrier. The free-floating mass may be slidably disposed in the housing. A length of the free-floating mass may be less than a length of the interior of the housing between the cap and the first end.