Personally I really like the Pyrodex P as a powder. Granted it is dirty, but
no matter what you shoot you have to clean the rifle. Pyrodex P burns cleaner then RS for sure. As for the American Pioneer Powder, after my last testing with a new pound of the 3f, I'm afraid to say they lost a future sale from me. Maybe the APP 2f will shoot perfect, so while I am not impressed with it does not mean it will not shoot excellent groups for you. I have one more rifle to try APP in and then I will just blow it off for fun shooting. Now APP is a very clean powder. No swabbing, and clean up is easy. Maybe APP 2f will really work for you.
If I had me an Omega that did not get nasty crud rings from the use of Triple Se7en 2f powder, that is the stuff I would buy to shoot. 100 grains loose and a 250 grain shockwave and I'd gamble you are going to have a good shooting rifle and deadly load. If my rifle got the dreaded crud ring from 777, and I did not want to swab all the time, then I would get a pound of Pyrodex P and shoot the same, 100 grains and the same projectile. Both of those would be safe bets.
Actually, I'd get one of each of the powders mentioned and send lots of time of the range.