The 7mm Altius build
Chambered in 7mm Altius (54r Improved necked down to 7mm) 27" Hart barrel Athlon Argos scope.
Here is a graph to illustrate the ability to keep heavier bullets supersonic for longer distances. The blue line is a standard 54r shooting a 168gr SMK at max potential. The red line is the 54r Improved shooting a 174gr SMK at max potential. The supersonic range of the bullet is extended in this example, by approx 450yds.