Techie Question---Scope Rings

[Omaha-BeenGlockin]

Will a 30mm scope tube sit lower in a set of low scope rings than a 1in tube scope in a set of low scope rings because of the larger diameter of the tube??

Or is that taken into accout at time of manufacture??

Exact situation:

I have a 3x9x42----30mm tube scope----that I want to mount on a Ruger 77 Compact rifle using Leupold rings.

Manufacturor states that the outside objective diameter is 48.7mm.

Do I need medium---high ----or super high rings???

Leupold's mount selector isn't much help----they have no scopes with a 42mm objective with a 30mm tube-----also I think their scope are "thinner"
inside to outside than the European scope I want to mount.


Thanks for any help.

 

[Art Eatman]

SFAIK, one-inch and 30-mm tubes are outside diameters. One inch = 25.4 mm. The centerline of a 30-mm tube is thus 2.3 mm higher than a one-inch tube, or some 0.091 inches.

So, you're gonna be almost a tenth of an inch higher in centerline with a 30-mm tube, and the extra one millimeter of objective lens radius shouldn't hurt.

Since I've always used low bases with a lens of 40mm, I'd guess those would work for you.

Most shops, if you don't tear up the container, will take back a wrong size; buy a set of low bases and a set of mediums, maybe?

FWIW, Art

 

[JohnMc]

Depends on the rings.

At least for some Burris rings, the .09" is taken into account, as the idea should be to base the calculations on how much clearance the largest diameter part of the scope has, that is, the objective.
Look at http://www.burrisoptics.com/rings.html on the lower right. The medium standard rings are 0.27 inches up to the base of the tube outside, while the 30 mm medium rings are 0.18".

Signature rings rule.

JohnMc

 

[Will Fennell]

www.leupold.com

Ohama,
Go to Leupold's website, and they have a "ring/base" selector, that will help you make up your mind. You input the rifle, scope, and type of bases, and it will tell you what hieght rings you need.

I've used it before several purchases, and it hasn't failed me yet.

 

[Amish_Bill]

The Leupold selector doesn't seem to have any options at all for the flat-top AR series... :-(
(at least not for what I would want)

 

[E=MC^2]

Also notice, Omaha, that many Euro scopes uses larger occular ends than most American-based companies. If you get the objective lens right down to the barrel there might not be enough room for the bolt to cycle, though, one good thing about the Rugers is the noticable arch they design into the bolt handle to help clear the scope. This is how it is on my 77MkII compact.

I have a 42mm Swarovski mounted on my Model 70 Win. Even though I have nearly 3/8" clearance between the objective lens and the barrel the bolt just barely clears the power adjustment ring on the occular end of the tube.

Also consider this clearance if you intend on using flip-up scope covers. This adds even more diameter to the occular end. If I use these on mine the bolt cantacts the cover and will not cycle. I'm using the Dual-Dovetails system with 30mm low rings.

By the way, with the DD system, measurments are given from the top of the base to center of ring. A 42mm scope will rest at the same height whether it has a 1" or 30mm main-tube. I have Swarovskis with both tube diameters and find this to be true. Of course I have no idea about their Ruger-style rings.

Don't consider the larger occular lens to be a drawback to Euro scops. I find it gives a much larger picture than scopes with a smaller eyepiece. Kinda like the difference in, say, a 21" television screen to a 27". It aids alot in lowlight conditions, I think.