Rigby, I'd love to see more photos and data on your 10. My Tolley looks identical cosmetically but is non-rebounding and only a 5-dram gun for roundballs. 9 drams and conicals is a monster!

I fiddled with mine endlessly for several years before finding the right load. Rifling limited me to RBs, so in vain attempts to get the barrels to uncross I tried heavier charges of slower powders (thinking more recoil without reducing barrel time too much), light charges of smokless and BP in order to increase barrel time, etc. Factory ballistics for my gun were a 700gn ball at 1300fps, but my initial 5-dram load crossed 9" at 30 yards. Probably why I got a good deal on the gun in hindsight!

It seems like the normal rules with DRs don't always apply with BP bore guns, as adding velocity increases recoil and 'swing' but also reduces time in the barrel, and there's no good way I've found to predict which factor will be dominate. What a great excuse for spending more time at the range!

Cheers,
Bob