There are at least a couple of options, even if you don't cast your own. The first would be the pre-lubricated conicals from Buffalo Bullet Co. available from Cabela's and several other sources. They come in boxes of fifty in .36 and .44 calibers along with fifty felt overpowder wads.
Another would be the precast conicals available from Dixie Gun Works. These duplicate the original designs as used for Remingtons and Colts in commercially loaded combustable cartridges of the period. The use of either a lubricated wad under them or grease over it in the chamber is a good idea to reduce the risk of 'chainfires'.
I'm not aware of any currently made HP, either pre-cast of DIY, for C&B use. Frankly, expansion in soft media would be 'iffy' at realistic C&B velocities, even with pure lead projectiles. Deformation in the loading process would be hard to avoid, given proper chamber fit, and would add to the problem materially. Accuracy would suffer as well, IMO.
IME, the Buffalo product offers the most consistent accuracy with the least fuss. It's tough to keep the original designs concentric with the chamber and the nose profile on both the Remington and Colt designs doesn't fit the ram nearly as well, making it all-too-easy to get the bullet cocked or damaged.
FWIW, more than one of my replica .44s shoot much closer to POA with Buffalo conicals and 30 gr. Pyrodex pellets or 25-30 grs from a flask than they do with RBs.