I shoot the same loads from my Omega. Work out the variables. Here are my polly pointers. A new muzzleloading takes around 60 -75 shots to get broken in before you start seeing consistent groups.
1. Ensure your primers are designed for in lines and not the std Winchester shotgun 209 primers (bluebox). These primers are to powerful for in lines and cause inconsistent burn rates.
2. Be careful when seating the bullet on the pellets. You may be crunching them. Push the bullet down and just lean into the ram rod a little with your weight to seat the bullet against the charge. Don't smash it down like a piston. If you haven't done so buy the handle accessory that screws on the end of the 10/32 threads. Use a spin jag to load as it will align the sabot to your rifling.
3. Keep your pellets dry. They are extremely hydroscopic Any moisture will make them shoot different.
4. Cleaning: Be consistent. 2-3 wet patches between each shot then use the retriever from max muzzloading to get the plastic out of the rifling and follow up with a dry patch or 2.
5. Try changing to T7 powder (90-120 gr) for increased accuracy. 2-50 gr pellets may not be the sweet spot on your Triumph. There is alot of variation within the same box of pellets. You get what you get in a box of pellets
6. Reference the 2 websites below for additional info. Buy Russell Lynch's video's if you are truly on a quest for muzzleloader accuracy. MAX: Muzzleloader Accuracy Xperts SpinJag - The 2-in-1 Jag For Muzzleloaders