Seating depth changes the volume inside the case. Yes it can and does change velocity potential which means it changes pressure. Generally you have to be on the extreme side of things to see the changes OOOOORRRRR you are not in a velocity stabile node. Extreme is something jammed in the lands to .250 out (think factory ammo).
Most people, even today, still think 100 yard groups is meaningful for long range shooting. Shooting a OCW or other ladder and dialing the rifle to that range and tweaking seating depth to get that bughole is still popular. However, if you are not in velocity stabile node, or in between a node, you can easily see a ES/SD go to crap.
For those who tune by velocity stability and stay in the middle of the node, the seating depth tests usually have minimal to NO affect. Since we are on a hunting page my thoughts are this: at a minimum seat the bullet in the neck of the case 1 diameter width deep. This should give enough bearing surface to neck to ensure concentricity and consistency of tension. Seat somewhere between 10-50 thou off the lands, as long as it means criteria #1, and then test powder charge. If your mag is short for the freebore then seat to max COAL that'll run in the mag, test powder.
Ive been doing the Satterlee method for a while now and it always works for me. I have not yet had a velocity stabile node that didn't shoot well at distance, took no seating depth testing, and may even produce bugholes at the zero distance(50,100,200...your choice). Now my criteria accuracy may not be good enough for you. I am super happy with .5 moa off my bipod, prone, with a rear bag, in the field at 400-600. Once I feel I can print several .5 level groups at that range I'll take it to 750-1100 to confirm data.
