At present i'm using a Brno ZKK 601 in .243 which has been my dads rifle since I don't know when but been having some accuracy problems recently. Have gone through a number of different problem areas and sure it was the scope (an old Tasco 6 x 40 which I think is past its best). Anyway a while back he bought a leopould scope so thought I would straight swap it to the rifle. Apart from the fact that it is a 30 mm diameter scope, the taper from the tube to the front lens is so long that it sits ON the iron sights and hence not into the mounts. The mounts are Parker Hale 17 mm with a stop pin protruding down into the rifle at the front so couldn't just move them 'back a bit'. Rail is a 17 mm dovetail.
Anyway got some different mounts and mounted the scope behind the iron sights but after trying to zero, found that the bases had moved forward (not the scope in the rings) so that the scope was touching the back face of the iron sight (was previously about 2 mm behind before firing a grand total of 12 rounds). Mounts were definitely tight enough but not overly so to weaken them. Needless to say I got scunnered with zeroing and here I am!
Does anyone know of a way to secure bases without having to drill out a new stop pin hole? Don't want to do it but needs must!