Some things you might want to try instead of Powerbelts are the 460 grain No Excuses Conicals. They can be found at http://members.aol.com/noexcusesb/page2.html. Load them with about 85 grains of Triple Se7en. These are slip fit, so they load easy and what they hit is really in a world of hurt.

Another good projectile is the 375 grain Buffalo Bullet SSB sabot. These are a spitzer point with boattail back end. They are also a little undersized so they load real easy. I want to state, I do not have an Omega but I shoot a T/C Black Diamond XR which has about the same barrel with a different action. I shoot both of these and the accuracy is exceptional...