No issues at all with BP. I think their nemesis is penetration with high velocity. I hit a quartering doe at about 20 feet, over 1600fps. There was no exit so I wanted to recover the bullet. I couldn't find it even after going through everything with my fingers. I skinned and butchered the deer where it laid and came back with my metal detector. Went over the hide, carcass, and guts. No bullet but there were small lead shavings throughout everything, it disintegrated. Based on that experience I used the platinum PB for the elk. It did well enough but didn't exit on a perfect broadside hit at about 60yds, found under the far hide. With your deerslayer and bp wouldn't expect velocity over 1500 and on deer it should do well.
I have used Powerbelts when I used an inline.They are more designed for shallow rifling.They will work.I have killed deer with Maxi's,Powerbelts,and roundballs.None were any deader than the other when hit in the vitals.All gave good blood trails.I don't use the conicals for hunting for the simple reason they do shift of the powder charge if the barrel in carried down.Have to check often to make sure they stay down on that charge.If its raining I carry my muzzle down to keep the rain out.Another reason is Powerbelts cost around $15/20 rounds.If you buy RB's they are about $8/100 rounds.
A properly patched RB is just as accurate if not more accurate and kill just as well.
I shoot the 245 aeroptips in front of 5gr 3f BP and 90gr. 2f 777. I shot a 200lb boar with it and it did fragment with small exit but put it down instantly. I have found that the damage done has outweighed the times where there was no exit wound. Took 2 doe last year, 1 at 8yds through neck and one at 103yds. quartering facing, Both exited and no issues.
I did have issues with the hollow points. On several occasions the seemed to mushroom and do little damage without very deep penetration. Lost a trophy buck this way and then changed to the aerotips which seemed to give the penetration I wanted. I shoot all these from a GP hunter barrel.
There is one guy in our group that shoots a TC PA hunter carbine with the 245 grain Power belts and he uses 60 grains of powder. The guy never misses; kicks em up and bang flop everytime. One year he was right beside me in some real thick stuff and up hops this deer taking off as fast as it could; old Duane smacks em on the second bound. Down and out right there. I never shot them in my rifle but I don't think you want to push em too fast; they are soft and expand no matter what; if you don't push real fast they will probably exit.
I use them in my Lyman 54 flinter over 90 grains of 777. They shoot well and I have never had problems with ignition. They can be easily pulled from the barrel at the end of the day with a ball puller since they have a hollow point.
I killed a mature doe two years ago with it. It fragmented, but I hit her high and spined her. Fragments penetrated the lungs and she did go right down. The PB did make a mess of the front third of one backstrap. My daughter was ticked about that. She loves backstraps and noodles.
Jester - 5 grains of BP? Never thought to do that....I assume you get faster ignition, right? Probably not much BP residue with small amount of BP. Interesting...you always learn something when you visit HPA!! Thanks!