the breech lock unit has a housing in which a strike hammer is mounted so that it can be pivoted around a shaft . a drive lever can be pivoted on the same shaft to a limited extent in both directions with respect to the hammer . the hammer is biased by a spring against the one stop with the lever . connected to the lever is a connecting rod which is biased by a striker spring and in the base position is in contact with a stop surface on the housing . the configuration described above makes possible a slim construction and optimum drive conditions . a plurality of functions that conventionally require separately installed components can be realized in the one breech lock unit .