Re: i bought varget...
When initially testing for pressure and velocity, I load 1-3 rounds at the increments I want to test the first time out to find the velocity range for that particular rifle.
I use a chrono to see where I am at, velocity wise. If velocity is not where I want to be, I will just shoot that one and move on...no sense wasting bullets, powder, etc. Each round is a sighter as well.
Once I am on target, for accuracy, I shoot round-robin to find the accuracy node. That is one round at each powder increment into a different bullseye....then repeat 3 times. With a little luck I might find the right load with a total expenditure of about a dozen rounds.
You might want to stick with one type of brass the first time out. The BH...it's a known quantity. I just seat to mag length.
39gr is a low starting load for BH brass. 44gr Varget behind a 168 should be comparable to Fed GMM...it's not a max load in any of my rifles, but usually accurate. With a new rifle, or a new jug of powder, I might start at 42gr in a new rifle just to be on the safe side. In that case, I might load 1 round each at 42.0 and 43.0 and 3 rounds each at 43.5, 44.0, 44.5, 45.0, 45.5.
By looking at the target, one of those should be an obvious winner.
42gr happens to be Hodgdon's recommended start load.
Look
here and see what makes sense to you.
TC