How much powder should be used in the Thompson Center white mountain 50 cal carbine?

For a target load or plinking I use 45 grains of 3F powder. For a hunting load I have used up to 110 grains of 2F with a 320 grain maxi hunter ball. I found 75 to 90 grains 2F for round ball out to 100 yards+/- works very well as a hunting load with the white mountain, Penn hunter and tree hawk short barrels. Any more and you are expelling unburnt powder from the barrel. You will have to experiment a bit to get the best load for what distance you intend to shoot and the ball / bullet weight and type of powder you use. For example you select Goex 2F powder and a .490 diameter 175 grain round ball with a .015 thick patch, and you want to shoot a target between 75 - 100 yards. Start out with about 50 grains of powder and work from there to find what powder charge gives you the most constant groups. The key is consistency in loading, the more ritualistic you are in the details of loading the more constant your shots will be.