If your stainless Omega is like mine it is not going to like 777. I would try to get some American Pioneer Powder or Black Mag3 (I prefer BM3 but it is difficult to find as yet because it is fairly new). If you cannot find APP or BM3 I would go with the Pyrodex either loose or pellets. (I prefer loose powder). Make sure you do not use Federal 209 primers as they are way too hot. Try CCI primers;if not avaiable use Remington;if not available use Winchester. Start your loads at about 80gr. and work up in 5grain increments until you get the best groups. My groups seem to be the best at about 100gr. of powder with 295gr. Powerbelts. Much more than that and the groups open up. You may have to shoot several powerbelts before the barrel smooths up. Stainless tends to be a little more rough than the blued barrels. I lapped mine to get rid of the rough surface.