I introduced the cast off on my 870 by using successive narrower strips of painter's mashing tape inserted between the stock and the action building to the thick side on the edge. It only took a few strips to get to where I needed to be. Once there, I trimmed the exposed excess with a razor blade. Sounds delicate, but it has lasted about thirty years. Did the same with a Benelli Montefeltro before they came out with changeable inserts to do the same thing. My Superposed 20, the Benelli 20, and the 870 12 now all have a very similar drop and cast. I can go from one to the other without missing a beat.

Best wishes,

Jack

"Do not blame Caesar, blame the people...who have...rejoiced in their loss of freedom....Blame the people who hail him when he speaks of the 'new, wonderful, good, society'...to mean ,..living fatly at the expense of the industrious." Cicero