I Googled eye relief and found this:
The Essentials Of Eye Relief
Scope cuts qualify as "avoidable collisions." The trick is in getting the full-field picture without getting a lot of grief.
By Craig Boddington
John Lazzeroni aims one of his L2000 rifles in one of the worst possible positions for accentuating recoil: prone, cramped, uphill. In a situation like this, there's almost no such thing as enough eye relief.
Not too long ago a riflemaker sent me a powerful, flat-shooting rifle to play with. Being well intended, he sent it fitted with a powerful scope that, optically, I rate as one of the finest in the world. The problem was, I couldn't keep away from it. No matter what position I shot from, the doggone scope hit me between the eyes at least two out of three shots. Fortunately, it was well padded with rubber so it didn't actually cut me. Instead, it was one of those scopes that my old friend Bob Milek (who really hated recoil) described as one that would just "bludgeon you to death." Needless to say, I couldn't shoot the rifle like that, and if I kept on shooting it that way it wouldn't be long at all until I couldn't shoot anything without a flinch. I took it off, returned it with gratitude, and replaced it with a scope costing perhaps only a third as much; definitely inferior in optical quality, but offering a whole bunch more eye relief. Eye relief, by the way, is very simply defined as the distance between your eye and the scope at which you get a full field of view. We don't think about eye relief too much when we're shopping for scopes. It isn't easy to check until the scope's on the rifle. And what looks like enough may not be once you start shooting. That depends mostly on how much recoil you're subjecting yourself to, but also to some degree on how you shoot. Me, I'm a stock-crawler, and I have permanent scars on my forehead to prove it. High-magnification scopes tend to have less eye relief than a standard hunting variable in the 3.5-10X class. This is not a problem on a varmint rifle; given reasonably proper shooting form, no .22 centerfire (and probably no 6mm) should ever cut anybody. Low-range variables like a 1.5-5X tend to have the most eye relief, which is a good thing because they are the most likely scope to be mounted on big-bore with lots of recoil. One of the problems, however, is that many shooters are now mounting extra-powerful scopes that used to be considered varmint scopes onto powerful rifles intended for long-range shooting. The three-inch-plus eye relief that is most common is not enough. Sure, you might get by with it on the range, but from weird field-shooting positions you are very likely to get cut. And, come to think of it, weird shooting positions can transcend gun weight and recoil considerations. The worst scope cut I ever got was from a standard .30-06 with a standard 3-9X scope--but fired from a cramped prone position. I got the deer, but I badly needed stitches that I didn't get. Sadly, I don't think most manufacturers pay much more attention to eye relief than the average scope buyer, and when the buyer gets cut, the rifle is more often blamed than the scope. Many scopes--including some very good ones--don't have enough eye relief for all of their potential uses. One of the pitfalls, too, especially now that variables are almost universal, is that eye relief can change as the magnification is increased or decreased. The 3 1⁄2 inches you get at the lowest setting may be enough under most field conditions, but the three inches you get at the highest setting may be inadequate.
ust how much eye relief you need depends on rifle, caliber, gun weight, how much you shoot and what positions you're shooting from. And given the infinite number of field shooting positions, there are some positions where you simply can't get enough support and/or flexibility to prevent being cut. In the excitement of the moment you may not be aware of this. And--trust me--it's even worse when you know what's going to happen up front and you're forced to decide whether the shot and the animal are worth the pain.
The ideal, of course, is for it not to hurt. Above the varmint rifle level I'm pretty sure you need at least 31⁄2 inches of constant eye relief in order to keep away from the scope under most conditions. More is better, but it's rare. So I was thoroughly delighted to learn that Nikon's new premier Monarch Gold line with 30mm tubes (and 30mm internal components and optics) incorporates a full four inches of eye relief, constant across the power spectrum.
The glass is great, the ruggedness is superb, the adjustments are precise and the eye relief has been as adequate as most competitors. But the company's introduction of a 30mm scope with four inches of constant eye relief is, to me, pretty darn near revolutionary. Currently there are just three models: 1.5-6X, 2.5-10x50, and 2.5-10x56, each with a choice of a Nikoplex (which resembles a standard plex) or German-style reticle. I'd like to see something between a 3-12X and 4-16X in this lineup, but until I see one, my plan is to put one of these 2.5-10Xs on a .300 magnum and another one on a .375 or .416.
I'm tired of scope cuts!
End of quote
I guess you can see that according to this well known gentlemen, 3" of eye relief when using eye glasses on a 30-06 is not enough. I wanted to do it right, so, I took the scope back and bought a Ziess Conquest 3x9x40 instead. It has 4" of constant eye relief. Now, regarding the 25-06, I am wondering about it too.....
