It looks like .562-5 in the grooves and .542 on the lands(rough measure but the best I can get). The conicals I wanted to use are .552. I'll have to see if I can dig the bullets back out to see how deep the lube grooves are. These are not t/c maxi's and have the shallower grooves so probably no go. If I can make it shoot patched round balls well I'll be very happy, but may still try for a conical load for deep penetration on the hogs. Thank so much again for the help. I never thought about the depth of the lube grooves in equation.
As for the hogs, a .54 cal. ball will work wonders. I would not even think of using a slug. To use a slug being .005" larger than the bore, one would have to pre-engrave them to get them to load, I would think.
If I was 'sold' on trying slugs, I'd try the .54 calibre Lee R.E.A.L. bullet that has tapered sides. That one will load well - the whole question is will it be accurate enough and will it shoot cleanly enough to allow subsequent loads. I would lube it (fill the grooves) with Lyman BP Gold or Steven Paul Garby's SPG. Alternatively you could use 60% Beeswax/40% Vaseline - yes, I know "Vaseline" is Petroleum gelly - I don't care as it works amazingly well as a bullet lube with black powder as the propellant. It has shown to be just as good as both commercial lubes mentioned, in my BP rifles and also when used a lube cookie.
Your .54 should shoot perfectly well with round ball and a decent patch. For hunting animals I figured needed better penetration, a WW ball of .526" with thick patch would do the trick. Still well over 200gr. and with a charge in that 48" twist of up to 110gr. 2F - would shoot very well indeed, if the barrel is a good one - most are. A 10 ounce denim patch would be what I'd use with that hard ball. Guys up here use that same thickness patch 10ounce denim) with .530" and .535" balls in their .54's with pure lead. Lots of compression in the grooves, clean and accurate shooting.
Your .010" rifling will work well with patched round balls. Hard to say what it will shoot like with bullets. Keep them short- 48" IS a round ball twist, not a slug twist. When you shoot slugs that are too long for the rifling twist- they may shoot accurately enough, but being on the ragged edge of stability, will likely tumble on impact and not travel in a straight line inside the animal, As Lt. James Forsyth wrote, "shirk the bones and course through the soft parts of the body, making neat wounds, rather than like a round ball smashing the bones asunder and creating most grievous wounds". He was very much against "soft concials" for dangerous game. "Conicals, of necessity, have to be made soft to take the rifling, whereas the spherical ball can be hardened and thus out penetrate the conical".
It was not until the advent of modern breech loading (ctg.) guns where hardened conical bullets would out-perform the spherical ball, within hunting ranges.
He did note, that conicals were very much better than spherical balls for wounding game that was always collected with the use of dogs - to run them down and bring them to bay.