Thanks.
Dana, I split the coupling nut about 1/2 it's length and slid it over the tang and pinned it so it would wobble a little. That wobble allows the butt cap to level itself. I sometimes pin the butt cap along with the finial machine screw, but this time I did not. I hollowed the butt cap as I mentioned and the hollow is irregularly shaped so the epoxy will fill it in and wont let it move. Of course, you have to overfill it a little or prime the butt cap with epoxy to make sure it sets up into it.