A firing apparatus (1.0) for a projectile-firing weapon of the type comprising a barrel (8) having a bore therein, the firing apparatus comprising a breech assembly (2.0) adapted to be secured to the barrel (8), a firing mechanism (5.0) adapted to initiate firing of the projectile from the bore, and a valve means (4.0)adapted to allow air within the bore, between the projectile and the firing mechanism (5.0), to be expelled from the bore during loading of the projectile through the bore.