I just instructed seminars on the Omega, we shot three T/C's and a Disc rifle out to 250 yards with excellent accuracy. Secret is to use a consistent loading procedure, which includes swabbing between shots. We used one patch moistened with T/C #13 solvent, then a dry patch, then loaded and fired, the one moist patch etc. Moist is barely moist to the touch.
The Omega works nicely with 3/777 and the 250, ,but fact is it will work with any load if you follow the instructions.
Good luck with your shooting.