I'm hoping to work up a round ball load for my JP Sauer 16x16 over 8x57 JR. I have a mold ordered for the rifle now I need to decide what size ball mold to get. The left barrel mikes .637 at the muzzle and the right .642. The left is the one I want to work with since when you select the rifle the rear sight pops up and the front trigger shoots the rifle and the rear the left barrel. A Rem sp16 wad when pressed into the muzzle and measured with a caliper is .600. I know that is a size Lee makes but I was wondering if I should go 1 size smaller and patch to fit to be on the safe side? I see that Lee also makes .575 and .562 sizes. I'm also unclear about load data. I have read that you can use the data for the same weight of shot. So I would use 7/8 oz as it is the closest? Longbow has mentioned using card wads and cream of wheat to cushion the ball I had planned on that so I would add that weight to the ball and go from there? I really hope to get a load to hit the sights at 40 yards or so. I found a five pack of Rem slugs and so far only shot 2 offhand at 30 yards. They hit about 3 1/2 inches apart and to the right. They would have both killed a deer at that range. I could have been pulling the shot though. My shots are close so I'm not asking for great accuracy Need to try some more off some sticks or a standing rest. Any help would be appreciated.