RE: 50 cal. thompson center
As stated, depends a bunch on your barrel's rate of twist
My Pennsylvania Hunter with 1-66" twist, 32" barrel really likes this load:
.490" round ball
.015" patch lubed w/bore butter
80 grains Goex FFFg
1/2 pan Goex FFFg prime
Missouri Longtrekker (Rich Pierce) 5/8" flint