I fit all extractors by hand. I start by doing a visual and just get it roughed in close. Then I paint the extractor with a black felt pen and wiggle it in place to see marks were it's interfering. I then remove metal and mark it with the felt pen again, and try it again. Repeat until is slide in place and I can close the action and know it clears. Did a Ballard extractor yesterday and it took probably 15 tries to finally get it fitted and the breech block clearing. Once in awhile I get lucky and fit one in a half dozen tries.