To index a screw, you can hand tighten it in a electric handdrill and useing a small file on the under side of the head take a little off. Try it, and take a little more off if it isn't right. I've never noticed the head sitting lower than the surface around it by useing this method. Paul

The joys of galvanic reactions. This is not gun related but one of those things that shows the truth of "Murphy's Law". The house we have was built in 1983. We purchased it in 1996. The basement became my "play" area. About 8 years ago, I was down there and thought I could hear water running when I knew nothing else was going on in the house that should make me think that. I started to investigate. I eventually found a covered sump hole and had a look inside. I could hear the water running there but not see it. The hole is only about 8" deep with a sand base. I moved a bit of sand and found the water supply line to the house was in there, as well as an outlet. I kept moving sand along the water line (copper) and encountered a 2" common nail with head resting against the line. I also saw water finally. I lifted the nail and suddenly had a lot of water spraying me and anything within ten feet. Dropped a bucket over the line, called the water utility, had the main shut off, cut the line and spliced in some new copper. Water back on and no problems since but that leak had been going on for years and created an underground mudhole. As that has dried out over the last 8 years, the cement floor has heaved and cracked and the teleposts (jackposts) have needed adjustment to re-level the whole house. All for the sake of a nail that ended up resting against the copper line.

Based on that, maybe copper shims for gun purposes would only see the shim needing replacement in a few decades. I'll leave that to the metalurgists to verify.

Cheers,
Jack

Shims are not the right way to do it. You wouldn't take it to a gunsmith and expect him to fix it that way. Take the screw out and lose the shim and you're back where you started from. It's very easy to take a bit off the under side of the head. Paul

I think you've got it bass-akwards. The shim is intended to raise a screw which is below the surface.
Taking more stock off the back side of the screw will sink it further below.

For the amateur - use a non-copper shim

Jack, You should be glad it was a the well line and not the copper line off of the oil tank:eek: