Any muzzleloader shooter know's that a few grain difference here and there means NOTHING, black powder is measured by volume not weight like smokeless rifle powder.
Any body weighing blackpowder has too much time on there hands.
Every single rifle is different, however, powder makes very little difference from gun to gun as far as accuracy, ignition is a very different matter, bullet type is where the major accuracy difference comes from, you can nit pick BH209, T7, pellet's vs loose all day and you will get different answer's
The first couple responders on here are right on, it is totally up to you, depends on the model, make of rifle you are shooting due to bbl manufacturer differences and so on.
Loose powder does provide a greater degree of accuracy because it gives you a more consistant burn, burn rate's in black powder shooting dictate how accurate a gun is gonna shoot more so than the brand of powder. That is why those of us that not only hunt with smoke poles but shoot them competitively shoot loose powder. Make sence?
1. Sabot's shoot best because they have the most bbl wall contact, some conicles also fit this requirement.
2. loose powder because of the BURN RATE being so much quicker than pellet's.
3. whatever type of ignition you use, use the hottest you can get with the exception of 209 primers then stnds generally produce the best accuracy.
One last tip, never, ever, hunt with a clean rifle. Alway's hunt with a fouled bbl in your muzzleloader, try it, shoot a shot with a clean bbl (fresh from the bath tub) and then shoot a three shot group with a fouled bbl. See what happens. It has little to do with the clean bbl, it has everything to do with the seal of the breach plug. You will alway's have different, more consistent pressures from a rifle that has been fouled.
I hope this help you out, good luck this fall.