Wanted to revive this conversation over 6 years later if y'all are cool with that..
I found myself making a wonderful trade last week and got over 10,000 preprimed new 9mm brass (xtreme headstamp?), 10,000 new old stock 9mm lapua brass, thousands of projectiles, powder, etc... I'm loading 9 major with Federal SPM, but since I have all this preprimed brass now, do we think I could load those up for 9 major and just test velocity to see if I need to increase powder slightly?