Joel
I have a custom 7 RUM with a 32.5" bbl and have tried many different combinations with the 168 Berger. My accuracy load is 93.0 gr of Retumbo with a 215 primer seated to just touch the lands. The problem with this load is that I could only get one or two firings out of the case then the primer pocket opens up. Velocity is 3580 and every once in a while they don't make it to the target.
This is a long range live varmint gun shot in the warm weather months, so I decided to walk it down to see where the accuracy fell off.
I started with 93.0 gr of Retumbo, changed nothing else, and worked all the way down to 83.0 gr in .5 gr increments.
Surprisingly it shot in the .2's all they way down, and velocity dropped to a comfortable 3200 ish. It now lives at 85.0 gr and 3250 fps.
Joel