

I have limited myself to one bullet, a cast lead Saeco 1E 306 grain, because that's the mould I have. Powder has mostly been Goex Fg because I have a lot of it on hand. Several different primers have been tried, with powder charges of 50, 55, and 60 grains by weight.
Perhaps the single best thing discovered is the absolute necessity of a 1/16" grease cookie under the bullet. Without it I could not get a cleaning patch & jag into the bore more than a few inches at a time after firing just five shots. With a grease cookie I can easily run a patch through even after twenty shots. It really keeps the black powder fouling soft.
Best load so far using Starline .45-70 cases modified to fit the .45-60 has been a Winchester Large Rifle primer, 55 gr. by weight of Fg Goex black powder, a milk carton wad, a grease cookie, another milk carton wad, and the Saeco bullet sized .459 using SPG lube. The powder is dropped into the case through a 2 ft. drop tube, then further compressed about 1/8" with a powder compression die before the rest of the components are added.
Here is a picture of the best target shot off the bench at a measured 50 meters:

Shots 1,2, & 3 went into 3/8". Shot 4 was a bit left and opened the group to 7/8". Shot 5 was right of the others and opened the group to 2 1/8". I don't know if #5 was caused by fouling build-up or if it was just me. Chronograph showed AV 1046, Es 32, SD 12, AD 8.

Shasta