Re: 168gr Bergers out of a 7mm RUM
Start with 85 gr of Retumbo, and work up from there.
I have a custom 7 RUM with a 9 tw, 32" barrel that spits out the 168 Berger at 3250. I had to back it down as they were coming apart at the higher velocity.
If your rifle does not like Retumbo, try RL 25 or H-1000.