Hi Thunderbox, Just looking at your pic of the sight pivot pin in place, at the risk of sounding like a twit, it seems to have a larger diameter than usual, and if so would that close the gap enough to cause the problem? My pin dia is .1425`, and the very small clearance under the pin to bolthead (on the 6 just cos it was handy and fits the 55 too) is .026.?