For example, I use a 15 bore ball, .677" in WW alloy with a .030" (caliper) denim patch (12oz). These run .025" with my mic. and .026" with Taylor's mic.- all measurements compressed of course, as that is what the lands do. I use this same patch with a .684" ball, a mite tighter than some people load - but it's amazingly accurate, shooting sub 1 1/2" groups at 100 meters off a rest.
For WW or hard alloy balls, I like the Jeff Tanner moulds. When I trim the sprues, I use wire strippers (plyers-type with the little cuttouts for different size wire) In cutting and twisting motion, the sprue is all but gone, and a single swipe with a wood rasp makes for a perfectly round ball, no sprue at all, so it can go in, any which way.