shep mo
Some of what you might shoot depends on the rules in your state...
You will find out that your Omega has a tight bore and because of that you will need to use TC Mag Express sabots, Harvester regular sabots, or MMP HPH-24 sabots.
I use 100 grains of Triple 7 -2f powder but again that is something you will have to find out what yougun likes - maybe start at 90 grains and work up to 110 (10 grain increments) see which one gives you the best accuracy.
For me and only my personal opinion, I would suggest a Speer Gold Bullet, .452 caliber - 250 grains weight.
Powerbelts are certainly the easiest projectile to get started with but I would only use them to start shooting and to break in the bore a little bit. A lot of people love them for hunting a lot of people do not trust them for hunting I am one of the latter, but you will have make your own decision.
My Omega is a SS/Grey Black Laminate stock 50 cal...
Hey! good luck