I don't know if it's been done before, but I used a sliver of 1" copper pipe to make a zero stop for my SS scope. It's a little big as is, so I cut a 3/8" wide piece out of the ring and bent it closed a little more and now you can see the reference marks on the scope's elevation turret. . Mine needed to be about a .190 long piece of tubing and that still gives me about 4 min to go down in case my load changes or something.