When using anything Magnum, I generally use a magnum primer, for consistency as was previously mentioned. However, for Magnum calibers I generally use the following powders in preference, H110, WW296, 2400, and IMR4227, I've tried the standard pistol primers on 4227, but didn't get any type of consistent accuracy shooting at a gong, switched to the magnum primer loaded rounds and noticed an incredible increase in hits. BTW Hondo 60 I do appreciate the testing it definitely answered some of my questions.