Jeremy,
I have used Retumbo in my 6.5x284 with Berger 140 gr VLD's. This load at .075" off the lands, 59.0 grains Retumbo with Wolf magnum primers gives me 2990 fps with a 24" barrel.
With the Hornady ELD-X 143's, I am doing a jump test first at .010", .020", .030" and .040" off the lands with a charge of 56.5 grains Retumbo and CCI BR2 primers.
I know this does not follow Berger's thought process for seating depth adjustment, but I don't want to give up case powder volume.
Once I find the best bullet seating adjustment, I am going to work up towards 59.5 grains to find my max pressure load.
I will post my results when I finally get out shooting again.gun)