ptf18: That sounds more or less like what I'm doing but I'm going to be estimating the thickness of the shim required with main screw in place, then checking visually for alignment of collar/ threads as I sand the shim down. I don't think altering the hole afterwards should be necessary or advisable. Unfortunately I won't be doing this for a while as I'm stuck in Kaua'i for a few more days on a much needed getaway from winter. I'll be posting some photos of my Siamese Enfield repair project after I get home.

Ridolpho