Carl,
I shoot an Omega .50 and may be able to help. Max load per T/C is 150 grains of either blackpowder or Pyrodex RS. I shoot strictly loose powder.
Triple 7 FF would be a good one to start with. You'll have to back the max load down by
15% per Hodgdons site.
http://www.hodgdon.com/loading.htmlI have a 110 gr. load that shoots sub inch 100 yd groups with Precision Rifle's Dead Center 250 and a 120 gr load that shoots the same size group with 300 gr DC bullets. Shock Wave's, one and a half inch groups with the same powder and charge. If I'm shooting well, I can get it to an inch.
With T7, start with 90 grs. and work up at 5 gr increments. Your Omega may not like what mine does. They're all a little different and picky. For bullets, try several different brands and weights. Mine will shoot 300 grain bullets, on a whole, better than lighter ones.
I'm playing with Blackhorn 209 and still working on "tuning" some loads. Max load is 120 grs. per Western Powder's site. 110 grains is my max here.
I never shoot over 120 grs., other than BH 209(less), in my Omega. The gain in velocity and terminal energy is marginal at best and the recoil is milder too.
I'm currently working on loads with Harvester Scorpion 260 gr bullets with T7 and BH 209 using their crushed rib sabot.
I'm testing all the time.
If you want to get more detailed info, feel free subscribe to my free newsletter. I talk about load development, accuracy and many other topics in detail and post range testing results too. Just a suggestion.
Be sure to read the manufacture's instructions regarding loads.
Hope this helps a little.
Paul