Glk21C,
I will start at 1.160 and go up/down as needed to fit the magazine or until the bullet hits the rifling.
Garmil,
I thought all X-treme bullets are heavy plate. I guess 124's are iffy at IPSC Major?
Thanks for all the replies, please keep the info flowing. Right now I will be starting with 6.4grn of AutoComp, in a new Starline case with small rifle primers.