I have always mounted optics as low as possible on my rifles, and have the gigantic collection of spare scope rings in every size/type/height that goes with that mild obsession. Perfection in my eye is an objective bell the clears the barrel by no more than 1/8-inch, combined with an eyepiece just barely allows the bolt handle to cycle properly with no contact. My guns are hunting rifles, not target guns. I don't take shots at extreme long range, and I strive for a rifle/scope combo that gives me a good consistent cheekweld that places my eye squarely centered behind the eyepiece; I rarely give parallax a thought and it is never a problem.
Now, we've all seen the hi-speed videos played in slo-mo that illustrate a gun barrel flailing like a bullwhip when a shot is fired. I've often wondered about just how much clearance is required to avoid contact during the firing cycle. Has anyone seen any measurements that clearly quantify just how much space is enough? I've recently mounted a scope onto a rifle using low rings, and it is a delight to shoulder that gun and eyeball a target through that scope with my cheek lounging on the buttstock...but the gap between the power change ring and the Weaver rail is so tiny that a sheet of quality printer paper slides through with some slight resistance. The rail is dished out on top to allow for increased utility of the iron sights, and the curve of the zoom ring hangs down into that little trough...otherwise it wouldn't fit at all. To be specific, the gun is a BLR takedown equipped with a barrel-mounted scout rail. The scope is a Leupold variable-power 1.5-4x28mm scout, and for correct eye relief the scope is mounted so that the eyepiece just clears the rear of the rail while the zoom ring is right over it.
This may be the most sensually perfect matching of gun and scope that I have ever experienced.
Is it too perfect...er, too close? 
Now, we've all seen the hi-speed videos played in slo-mo that illustrate a gun barrel flailing like a bullwhip when a shot is fired. I've often wondered about just how much clearance is required to avoid contact during the firing cycle. Has anyone seen any measurements that clearly quantify just how much space is enough? I've recently mounted a scope onto a rifle using low rings, and it is a delight to shoulder that gun and eyeball a target through that scope with my cheek lounging on the buttstock...but the gap between the power change ring and the Weaver rail is so tiny that a sheet of quality printer paper slides through with some slight resistance. The rail is dished out on top to allow for increased utility of the iron sights, and the curve of the zoom ring hangs down into that little trough...otherwise it wouldn't fit at all. To be specific, the gun is a BLR takedown equipped with a barrel-mounted scout rail. The scope is a Leupold variable-power 1.5-4x28mm scout, and for correct eye relief the scope is mounted so that the eyepiece just clears the rear of the rail while the zoom ring is right over it.
This may be the most sensually perfect matching of gun and scope that I have ever experienced.




















































