It's a dandy. I've had mine since 1981. Bought it in Germany to shoot in competition there. It oughta shoot a lot better than 9-ring, with a load it likes.
I recently dragged mine out of the safe where it had hibernated for 29 years (!) and returned it to shooting service: it still shoots as well as ever. One of my fellow Montezuma Muzzleloaders (Bushrod) challenged me to a 'duel' at the last match - he shot his original Manton percussion dueller, and he set the course of fire: 10 shots at the NMLRA pistol bullseye target at ca. 15 yards, with the 'seconds' giving the command to fire and counting seconds to 3; the shot to be fired from the low ready and within the count period, followed by 5 shots at a 12" gong at ca. 25 yards under the same conditions. Sadly (for him!), he did not win.
Scores were: challenger; 90 and all 5 gongs - challenged (me) 95-3X and all 5 gongs. He said his honor was satisfied, but reserved the right to issue a new challenge if he found further cause for offence.
My original load (in Germany) was 8gr. of (I think) RWS 3F (came in 200 gram brown paper bags), H&N swaged .330" RB and tough, thin patch of a linen made for shoe linings (wish I still had some!).
Currently I'm using some of my original supply of the H&N balls with patches of Walmart unstriped ticking (.023") and 10.5gr. Elephant 3F - tight load, but shoots extremely well. I also tried patching with Walmart 'Super Muslin' .015", which works well, also, but no better than the ticking. Also tried some of the Hornady '0' swaged buckshot, which measures .320" and shoots nearly as well with the same loads, but loads much more easily, and the Hornady '00' buck, which is .330" and duplicates the German swaged balls, but is much more perfectly formed. I was also pleased to find that the Hornady buck is not at all hard: since it comes in a 5 lb. box (about 640 balls, in '00'), and costs only a bit over $25 retail, I'm gonna stick with that, when my original German ones are all gone.
Now if I can just find a really good flint dueller...
mhb - Mike