Drive assemblies for surgical clamping and cutting instruments, as well as surgical clamping and cutting instruments using these drive assemblies, are disclosed. The drive assemblies may include a drive member, a locking member mounted to the drive member, and a spring. The drive member may be configured to releasably engage at least one of a knife or a shuttle of a surgical clamping and cutting instrument for translating the knife and/or shuttle in a distal direction through a firing stroke. The locking member may be movable from a first position permitting distal translation of the drive member through the firing stroke, and a second position inhibiting distal translation of the drive member through the firing stroke. The spring may be configured to bias the locking member toward the second position.