A breech device of a hand firearm comprises a firearm casing, a trigger mechanism, a carrier slidably arranged within the firearm casing, and a breech block engaging the carrier and having a firing pin. The breech device further includes a tensioning element slidably engaged with the carrier and coupled to at least one follower pin engaging the firing pin and slidably engaged with the breech block. The tensioning element includes a projecting part having a forward-directed nose adapted to engage a stop detent on the trigger mechanism. The breech device further includes a tensioning pin slidably engaged with the carrier and the breech block.