Just a followup on eye relief. Granted, on a hard kicking, light, magnum rifle, long eye relief is a great thing. But I don't think that's always the case.
I've got a Rem 700 VSF in .308 that I put a Nikon Buckmaster scope on. Catalog says 3.6-3.7" of eye relief. I wish it were less. I mounted it in a pair of standard leupold rings on a one piece base as far forward as it would go. It's great for shooting off the bench, standing, or kneeling. For sitting and prone I could do with less eye relief.
I can shoot it prone without a sling, but with the rifle tightened in to me with the sling, I can't get my head far back enough to get a decent picture. I need to get one of those extended front rings so I can slide it forward about 3/8".
Remember, putting the gun up to your shoulder at the store may give the impression it's mounted just fine with respect to eye relief, but for some shooting positions you'll want less.