Terrill if you would like to try a .30x1.5" (308R2) I have a 20" barrel ported in the rifle position that I will sell. 1:10 twist and setup for 125gr - 155gr supersonic loads. You would need a set of 223 Rem dies for initial sizing and 300/221 dies to form the neck and shoulder. Being ported in the rifle position it needs powders 1680 or slower burning to cycle.
Barrel is chambered for cartridge on right, 300/221 is on left