The Noske mount came in different variations. The one I have
slides onto the dovetail base and is held in place by a screw that
has a large knurled head and comes through the ring assembly
from above. It seems to be made with very close tolerances and
is held firmly in place. It is not quick detachable like
those that can be released by levers. It is on an NRA Sporter
that I have never fired.