lemoyne

Well first off you have not discribed how tight your sabot is in your barrel after you get it started or how hard it is to get started. I take a new gun and take out the breach plug and try a bunch of different sabots it needs to be as tight as you can still load smooth [no pounding !] . Most TC Muzzleloaders use MMP-HPH 24 or a crush rib but there is a wide tolorance so be sure to get that right fit; too loose will shoot large groups too tight and you beat on them and they will go all over the place.
Due to barrel harmonics you need to start with 80 gr and increase 10 gr after a 3 shot group till you have the right sabot bullet and powder load to shoot good you might have to go all the way to 150 gr with some bullets and you will find some it just wont like. Some like different powders I use RS in the Omega and 777 in the Triumph and Pyrodex P in the System One you have to find what they like and bullets are the same way.
I would suggest you run the powder ladder with all the Shock Waves and the 250 and 300gr Gold Dot and some blue sabots from MMP and the 40 cal 200gr XTP. Try pyrodex both RS and P and 777-FF and FFF if it wont shoot some combination of these with the proper fit on the sabot then there is likly something wrong with the gun. Lee