GH ,I have 10, 14 and 21" 7tcu barrels. They are ALL picky about best (MOST ACCURATE) loads. While they will put any load from the other tubes into a 2" circle ,THE load for each will go under an inch!You are going to have to shoot a few groups to see what the barrel likes. I have found good loads with 748 powder and 120 grain bullets . A decent DEER load uses 139 hornady bullets. Even in a carbine barrel, you start to run out of powder capacity for a HUNTING load. Expansion will not be certain using 150 and heavier bullets in the 7TC/U.I have used a CAST 135 and 150 grain bullet for deer hunting with good success! H335,h4895 and AA 2520 are also good powders to try. There are too many good powders to list them all here. Any 10 or 14" load can be used in the carbine barrel, just start low AND WORK UP.
