My Omega shoots two types of bullets really well. They are the 300 gr Nosler Partition HG PP and the 340 gr DeadCenter by PR. Powerbelts shot like hell and if I could get a 4" group at 50 yds it would have been special. The XTP's, 250 Noslers and TC maxi Balls all shot poorly from my Omega.
The PR's with T7 pellets worked nicely and the 300 Noslers shot well with T7 loose.
So long story short........Experiment more. I've found a new home for the XTP's (with my Renegade)and the maxiballs and hunters are melting material for jig heads.
edit: I forgot the SST's didn't do all that great either at 100 yds.