Answer:
The maximum load would depend on what model it is, you can download manuals at the Thompson Center website www.tcarms.com, The manuals also have a recommended load. As for a load to start with I always start with as many grains as the caliber, 50 in this case, and work up from there depending on the weight of the bullet and distance you wish to shoot. You will find a "sweet spot" in your load that gives a consistent tight grouping. Every gun is a bit different, example my .50 TC New Englander likes 55grains, .50 TC Penn Hunter Carbine 45grains, .50 custom long rifle 60 grains, all using the same patch and bullet combo at 50 yards target shooting.