I'll admit that I know nothing about the T/C Firestorm, but since you mention 3f in the pan, I gather it is a flintlock.

You say you don't shoot much, but best accuracy is obtained with a 50/50 mix of 2f and 3f? Sounds like you must have done some testing. I am not a flintlock guy, so don't know if this is a common practice or not. I suspect it is not, and I really can't see the benefit. I also think you should be able to get better accuracy than 3" at 50 yds with some projectile.

What is the twist rate? That will tell you what projectiles "should" shoot best in the gun. If your twist is a roundball twist like in the 1:60 range, shoot roundballs. I'm confidentthat T/C will shoot some combination of patch and ball better than those ballets are shooting, and I'll bet you can use more than 60 gr of either 2f or 3f (but not a mixture). Based only on whatI have heard, I'd suggest priming with 4f and 3f for the charge. If 2f works you could use that too.

Others can be of more help regarding an exact load or patch/ball combo.