Comprises at least, a stock, a trigger mechanism and a barrel (1) partially covered over by over-moulded or over-injected material (2), defining therefore by said over-moulded or over-injected material (2) a first area or housing (3) for the mounting of a sound suppressor (4) following up or alongside the barrel (1) and a second area (8) at least wrapping around the part of the barrel (1), and that the sound suppressor (4) comprises: an inlet (5) wherein the barrel (1) is situated, comprising a support (7) of diameter equal to second area (8) on which it is fitted, with perforations (18) that connect said second area 8 with first area or housing (3) and an outlet (6) that comprises an attached stop (9).