RE: thompson pa hunter flintlock .50 cal
When I did some checking, I found that the PA Hunter is no longer in production according to T/C website. It has a 1-66 twist like I remembered, according to the site.
I have a .50 caliber with a 1-66 twist and it loves 70 grains of Pyrodex Select, a .015 pillow tick patch, and a .490 roundball. I have never tried any other load besides roundball out of it. I have never had a problem with a roundball taking a whitetail deer.
Good luck with the new rifle and welcome to the sport.