You may be experiencing a little spring back of the breech caused by how soon or late the sears grab on the hammers in your particular gun.
The cocking bell-crank hits the milled slot in the water table opening which causes a firm stop point for the opening of the breech.
Any return movement there may be after letting go of the barrels is the distance between time of cocking and time of stop.
__________________
B. Dudley
|