Larry,
What scope are you using?
I was shooting free recoil (I do have a recoil pad however) on my 308OBM until my Burris scope died. I would push the rifle forward to the stop with my shoulder then back my shoulder off to just the point of no contact.
I replaced the burris with a Weaver T6 (it must have a shorter eye relief ) Now I have to have what I would consider firm shoulder contact to avoid "scope eye". I am shooting 132BIB's and about 47.5gr N140.
Very interesting topic and I hope to learn a bunch.
Good Hunting
Jeff in ND