I've got a 1 1/8" .62 barrel (.615) and instead of shooting patched round balls, I want to try conicals. I'm looking at an N.E.I. mould #397A that is .610 and weighs 900 gr or .700 gr. (my choice). The twist is 1-30" and the grooves are .002" deep or .614" overall. The slugs can drop from mould up to .003" oversize for a total of .617". The old .600 N.E. was .622" I"m told it will work. I'm wondering if "pre-engraving" would be necessary since I don't have a press large enough to size them.
I fully expect some kidding but hopefully, there will be some legitimate advise. After all, when you get elephants in your back yard, you gotta do something!