OK here is the best advice you can get! Every rifle is diffrent so that being said if you hand load which I am assuming you do you have to do your own test.
I just did mine with my 300 win mag and 185g VLD it took 24 rounds. I loaded up 4 groups of 6 rounds at diffrent seating depths.
CCi BR2 primer
81.0g of H1000 (this is max load in most re loading books)
1st 6 was .010 off the lands
2nd 6 was .050 off the lands
3rd 6 was .090 off the lands
4th 6 was .130 off the lands
What my test showed me is my group was around 4" at .010 off the lands then it droped to 1/2 at .050 off the lands and started to open again at .090 to 1" and finaly at .130 the group was 1 1/2". All my shooting was done at 200 yards which is veary important 100 yards is no good.
This is what Berger recomends you do for a hunting rifle for a target rifle the test is the same but the seating depths are a little diffrent.