Just figured out a way to hold the mount in place....
Use a rear sight dovetail blank (sticks up above the surface of the barrel). This could be the "key" that you index the mount too.
JYD #123 The great one formerly known as Architect.
I am now a fictional British television police officer (currently a Detective Sgt) at Thames Valley Station. My governor is Detective Inspector Fred Thursday and it’s 1969.