Wow, I had no idea how accurate one could be!
It makes sense - - The long barrel, semi-auto Thompsons fire from a closed bolt, and this makes it a lot easier to stay on target.
iiwas, you write that you're "able to shoot the caps off of 20oz. bottles at 100yds with out a problem." I'm very impressed, both with your masksmanship and the accuracy of your Thompson carbine.
I went and measured the cap of a two-liter 7-Up bottle just now - - 1.20 inch (1-2/10") diameter by .775 inch high, including the collar that stays on the bottle once the seal is broken. This indicates you shoot sub-two-inch groups with your gun and some very accurate cartridges. Wow - - Better than a majority of iron sighted deer rifles with factory ammunition. Better than government standards for an M1 Garand with M2 Ball.
Have you mounted some sort of optical sight on your carbine? Using the factory sights, just hitting a 20 ounce bottle with a .45 bullet is mighty good shooting.
Best,
Johnny