Gene, Unsalted lard is fine, as is Crisco in small amounts. It's the "shaving" of a thin lead ring from the projectile that does the trick.
FWIW: Dixie Gun Works catalogs used to have a ton of information on loading C&B Revolvers.... probably still do but I haven't looked at a new one in several years.
Anyway, at one time there was a copy of the original loading instructions that came from the factory with every Colt sold back in it's day, and at no time was there ever mention of lube of any kind ever being applied on the bullet, or over the cylinder....the cylinder pin was mention as requiring lube, but nothing on the bullet, under the bullet, or over the cylinder.
We all understand the importance of lube, but few of us understand how much and where it should be applied.
All to often huge globs of grease is applied over the loaded bullet with no more effect than making a mess....if this is done in the interest of safety it must be remembered that "chain-fires" start from the cap / nipple end and not the bullet end.
The 58 Remington you mentioned is thought by some to be better than the Colt in preventing flash-over from loose caps, but that is somewhat subjective and often disputed by Colt owners.
It is also believed that snug fitting caps on undamaged nipples will prevent any chance of a chain-fire....Number 10 caps are designed for C&B Revolvers and should not be substituted for Number 11's in hopes of getting "a hotter spark"....they are smaller and fit the nipple much better.
Good luck and have fun with your new toy, at least one C&B Revolver belongs in every man's arsenal, IMO.
Uncle Russ...