A few years ago, in my TC Triumph, I tried Blackhorn 209 & think I used 120 grains (their max) and Triple 7 pellets. Tried 3 bullets, Barnes sabot, Hornady sabot and TC Easy Lad Shockwave. The most accurate was the 150 grains of Triple 7 pellets with the TC shockwave. About 1" group at 100 yards, my rule was 3 shots without cleaning. I used Remington primers throughout. For 3 pellet loads, its best to use standard shotshell primers and NOT primers designed for muzz guns.
Barnes was/is arguably the very best bullet by far; however their sabots require almost a hammer to seat after the first shot. They about to about 1.5" with both powders.
The Hornady also shot well, and seated the easiest of the 3.
During the day shooting the gun 18 times, I cleaned after each 3 shot sequence. I noticed no significant difference between cleaning after the Blackhorn or the Triple 7. In all cases, the gun was dirty and required a good effort to clean up. I also noticed no difference in the amount of smoke. If there was a difference, I didn't notice it.
Forward 2 years and still not liking sabots, I tried Platinum Powerbelts, as they're "designed" for 150 grain charges. They shot well, 1.25" at 100. Liked them and began using them. But, after shooting 3 deer with them, I'm back looking for another bullet. While I killed the 3 deer, I am not impressed with the terminal performance in terms of the bullet fragmenting and not exiting, even on a broadside shot on a small deer.
Anybody know of a sabot that seats nicely and allows for 3 shots without cleaning?