When I was shooting Hunter Pistol Silhouette, I settled on the .30 Carbine chambering in my TC. I used a 165 gr. home cast GC bullet. Powder of choice was RL-7, as I remember. I used a two powder scope. I would hold dead on chickens, pigs, and turkeys and would hold top of the back on rams. No sight changes necessary. The chickens were slammed off their setting perch clear back onto the backstop. It took Rams down decisively!
My best scores were 38's as I never quite made a clean 40x40. Had LOTS of fun, tho'.
My "heavy hitter" is a JD Jones barrel for .375 JDJ (.444 necked down to .375). Using a near case full of rifle powder this cartridge drives a 270 gr. jacketed bullet to near 2000 fps. It's a real handful to shoot but the ported barrel helps, a bunch. My best target with this one was shot at 25 yards on the timed fire target. I had a 100x100 with ten "X's". I could feel the recoil getting to me, so after the first five shots, I put the pistol down, and rested a bit before I shot the last five. Great fun, those TC's! Ohio doesn't allow bottle necked pistol calibers for deer, so I never got to try this one out for deer. Using the right bullet, I'll bet it's a dandy, tho'...
FWIW
Dale53