I shoot the Xtreme 55grs over 24gr of Tac through my 18in Mega SPR barrel for my 3 gun rifle and I get sub moa groups with mixed range brass conconsistently.
I also use the 147gr RNs over 3.3grs of Csb1 in my 9mm with great accuracy as well. I'm definitely an Xtreme Bullets fan!