Re: shooting the lyman deerstalker
No reason to start with full hunting loads, As Buckstalker said, start with 40 or 50 grains of powder. I would suggest 2f in the bore and 4f in the pan. But with moderate loads, 3f is acceptable in both. Many shooters have trouble getting over the flash from a flint or the poof of a cap going off, no reason at all to make the reaction worse by starting with heavy loads.
Most important is concentrating on follow through. Seasoned flint shooters concentrate so heavily on the sight picture that they don't notice the flash anymore.
Try your best to hold completely still for a count of four after the shot.
Flinters have a few tricks to loading that make shots more consistent. When you load, after pouring in the powder, use the ball of your hand to bump the side of the gun a few times. This settles the charge powder into the touch hole channel and helps speed ignition. Also, don't fill the pan with prime powder. It actually slows down ignition. The bottom of the pan should barely be covered with prime powder. Many beginners buy those cut/sawn expensive flints. In my opinion, they do not spark as reliably as a good gray/black English flint. When the frizzen is closed and the hammer (cock) is at half cock, the lead edge of the flint should be just a millimeter or two away from the frizzen face.
The patch-ball combination should not be so tight that you bruise your palm on the ball starter, but there should be some force required to start the ball. Unlike many shooters, I have good results using a heavy cotton flannel for patch material instead of that tightly woven drill that most use.
Trying to describe all the nuances of loading a flint lock could take volumes and you would learn faster in 5 minutes by watching shooters at a black powder match.
Powerbelts and other conical bullets are fine for shallow rifling. But if you have round ball rifling, they won't work that well or might even be impossible to load. On the other hand, round balls do not do well in shallow fast twist rifling meant for conical bullets.
What riling does your gun have?