Old Colonel: The rear spring loaded mount is in my opinion the easiest, but should be done last, matching it to the finished height of the front. When you have smoked it in vertically, smoke it again and let the spring loaded shim make a mark in the smoke. File (cut) the groove (slightly uphill) beginning above the mark and polish it to a final fit. Whatever you do, don't guess about what is going on in fitting things--let the smoke tell you the truth. Even clean out the carbon from the groove every time so that it doesn't give you a false sense of "tight."
The front one, to me is the stinker. There has to be somewhat of a fulcrum effect after the tilt-entry angle as the rear of the claw sits down in the groove. If there is not, the contact GOES AWAY. As the rear sits down, the top front of the claw has to elevate into firm contact with the angle at the inside top of the groove, at least that is how it was on mine. I suppose one could make it shorter than the opening of the groove and shove it forward, letting the rear mount hold it tight, but I wanted the rear of the claw (though rounded at the bottom corner) to brace against the rear of the groove, staying tight of its own accord. Don't be disappointed if you have to make one over. Get a good set of files (the ones used to make hardened dies are the best), down to the Swiss sizes, and good luck!
I think that Oscar nailed the source, if you want it all low, and do not desire an under tunnel for the iron sights.
Clearly, I had no tutor, and there may be vastly better methods to keep everything nice and squared up...I welcome all hind-sight over on the other thread... Steve
