AR Sponsor
Posted: 5/19/2008 11:45:48 AM EDT
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Hi all, I ordered a scope for my varmint/target(flat top) build. I am looking at the Burris XTR rings. it seems that the 'HIGH' rings(3/4") will fit my scope/rifle - But Burris makes an XTR ring in Xtra high(1") for use on ar15 flat tops. Why would I want/need this Xtra height ring(1") if the 'high'(3/4")ring will fit? I will not be installing a BUIS. the scope has a 30mm main tube and a 56mm objective. outside diameter of obejctive bell is 65mm. |
| The geometry of the rifle is designed for iron sights that are 1.4" above the rail. To get that same elevation for a scope, you'd need "ultra high" mounts, or whatever they're called by the respective manufacturer designed to give the same 1.4" elevation. Leupold calls them "Ultra High". With that height, your cheek weld etc on the rifle, with the scope would be the same as with the iron sights. Lower rings might work just fine depending on your stature, how you hold the rifle, etc. I'm average height, and the 1.4" rings are perfect for me. I've had acquaintences choose the lower ring height that seemed to be perfect, find on the range with hearing protection, that the ear muffs interfered with the stock. |
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Many people want their optics at about iron sight height, which is 1.4", as stated. Some people like non-magnified optics a little higher to get lower 1/3 co-witness. Unless you know you want your scope lower or higher than usual on an AR, you should be looking for a centerline height from 1.3-1.5". Since you don't care about a BUIS, you can ignore the clearance for that, which often requires a little more height, depending. Burris XTR are spec'ed to the bottom of the ring, not the centerline, so you have to add 0.5" (1") or 0.59" (30mm) to get the centerline height. Other rings (like Leupold) are spec'ed to the centerline. |
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