Actually, I used my TCU back in the late '70 through the late '80's for shooting handgun silhouette out of a Contender and later an XP-100. My 6mm TCU is the most accurate one I have, but I did shoot my 7mm TCU a lot as well, as it knocked down the ram a bit more reliably.
Both are exceptionally accurate, and brass life is... well...put it this way; I always took brass out of rotation that reached 10 loadings and then quit counting. I wish now I had kept track, as I'm sure some of them have been loaded 15 to 20 times.
Now I'm actually considering getting a barrel for my AR...
I'm thinking the velocities would be considerably better than out of my handguns.