This is going to look like a hi-jack, apologies, but I have one of those J.C.Lord sniders from Nepal. Mine is mint, and I mean that, appears to be unfired. There is a story attached, perhaps in a separate thread.

What DoubleD said about those guys over on Brit Militaria forums is spot-on.
Shooting Sniders is not straight-forward, due to the fact that the groove diameter is usually no larger than the outside case diameter at the mouth. Hollow-based 'Minie' projectiles didn't work because the skirt only expanded inside the case, and didn't take the rifling properly. Various tapered plugs were tried inside the hollow base to assist expansion as the bullet left the case, but results were not consistent.

In Australia, we use oversized bullets (carefully!) and the best I have tried is the 'Bumblebee'.
A friend of mine has a Bugg mold that throws nice slugs. At about .592 they will shoot clover-leafs at 50m from my 3-bander all day long.

The other option is to shorten the cases by an eighth of an inch or so, and custom-make (or modify) a mold for a heeled bullet, like the .22 Rimfire. Then the 'driving band' will take the rifling the instant the projectile starts to move forward on firing.

One thing's for sure, very few Sniders will shoot a conventionally-loaded .585 lead slug with any accuracy, hollow-based or not.

Hope this is of some interest.