Modern rifling is a bit different than the old hand rifled barrels where if you used a large load the ball and patch might "skip" over the rifling.
Pedersoli uses a very fast twist in it's 28" jaeger with a 1:24 twist, and they know it is going to be used for patched, round ball. They sell round ball and a round ball mold for it as well as conicals and a conical mold for it.
The projectile gets a full revolution plus a tiny fraction more before exiting the barrel in the Pedersoli rifle. Germanic rifles of the flintlock era sometimes gave a 1½ rotation to the projectile before it exited the barrel. You should be able to use a 60 or even 70 grain load in yours..., but you may find the torque of such a tight twist slaps your cheek a bit more during recoil than other rifles.
In 1804 a British officer writing a manual for what would become the 95th rifles mentions the fast twist rates of American and German rifles gave one a "disagreeable recoil", and he's probably talking about the torque from the faster twist rates.
The only way to know is to experiment.
LD
