I'm new to bullet reloading - have loaded shotgun for years. I got a rifle barrel liner for my 1882 Remington 10ga SxS and on it is stamped 10ga 40 - 2 1/2. A friend who is a gunsmith had me fire form some 30/40 Graigs. We slugged the barrel - .408 - so he had me order a 400gr Lyman mould that was .410 and gave me some Lino-type [ sp ? ] - I got booits that weigh 415grs. Looking at a some old data for the 40-70 Sharps I found - 330gr boolit , 23gs of 4198 had a MV of 1250 with no pressure given. The powder fills the case just under half way. With the boolit in the case, there's about a .400 gap between the two. I also have some large Fed rifle primers. I would think I'd have to reduce the powder charge by about 30% after looking at some data for 45/70 using 4198 when they went from 400gr boolt to a 330gr boolit and reduced the charge by that amount. Or would I be better off reworking the mould to throw a 330 boolit ? Should I use a filler over the powder ? I try to be careful about pressures seeing how I shot damascus barrel SxS's and keep my reloads low. Any help where am I going wrong - everywhere ? Paul