My Bro's first Shiloh Sharps, bought as a barreled action had only 1 1/2 thousandths deep rifling. We tried for about 8 years to get it to shoot black powder and cast as well as black powder and paper patched bullets. Nothing worked very well, even with linotype metal bullets, however black powder and jacketed bullets shot amazingly well with sub MOA groups at 100 metres. Both 500gr. Hornady bullets and 300gr. HP Hornadys would shoot cloverleafs at 100 meters. BP and cast or
patched bullet diameter bullet shot at best, about 5" to 6" same range. The success with jacketed bullet showed us this barrel would shoot, we just hadn't found that load.
I bought a few Paul Mathews books & read about the bore sized bullets AFTER patching & did this, in my Rolling Block .45 3 1/4" as well as his Sharps .45 3 1/4". Instant success - mine running 1.3" for 5 shots off bags at 100 meters and Taylor's rifle running 1.5".
We re-cut 2 moulds using a ground drill in the shape of the Sharps factory bullets, but of course they weren't tapered except for the ogive.
One mould, a 4-cavity Ohaus .44 mould we bored 2 different weights, 460gr. and 520gr. as well as a single cavity small calibre Lyman mould to a 400gr. bullet. Taylor's rifle liked the short bullet and so did he - a matter of reduced recoil. He used 100gr. 2F GOEX, grease cookie, then 10, .10" monopoly board wads then the bullet, case sized to just hold the PP bore sized bullet(bore sized after patching with MASKING tape).
Mine liked the heavier bullet. I used 116gr. 2F GOEX, grease cookie, .062" card, then the bullet, 520gr. patched to bore size. In Bell brass, 122gr. GOEX 2F, and same cookie and wad & bullet.