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Posted: 7/18/2010 1:48:44 PM EDT
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Just finished a built and looking for the best way to mount a Leupold Vari-X III 6.5x20 50mm on this upper:
http://i77.photobucket.com/albums/j76/bruchi007/dpmsupper.jpg It is a 223 DPMS 24" heavy barrel 1:8 twist and the idea is to shoot it from 300-600 yards, my understanding is that this type of elevated rail on the upper would help me in getting the most of the scope's range of adjustment elevation wise? The original option was a set of regular height Badger Ordinance rings but after test mounting it with a set of very cheap rings and seeing the extended eye relief of this scope I was all ready to order LaRue Tactical SPR-E LT-139 mount but the folks at LaRue tell me to use regular rings as this mount would place my scope way too high, buddy tells me to swap uppers on the rifle to a normal height one? I thought that was the idea of this upper was to elevate the scope sort of using a 20 MOA mount on a bolt action rifle for shooting at this ranges? |
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Quoted:
That's a tactical upper and has the added rise to help get an eotech of similar optic up for easier use. If you are going to mount a telescopic sight I'd get a flat-top upper. Thanks but I am confused here, DPMS sold this as a 24" Varminter upper and I had the notion that you put high power glass scopes on varminter rigs instead of "tactical" red dots? |
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The purpose of those uppers are to raise the optic to the proper height but it does not solve th issue of eye releif. The DPMS Upper does no have MOA built into it, a mount with built in MOA will be taller at the rear than at the front.
If you want the proper set up change the upper to a flat top and get the LaRue mount. |
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Mounting a scope low on an AR, as you would on say a Remington or Winchester bolt gun, usually doesn't work too well because it's too low for most people to use comfortably. The buttstock configuration of a AR forces your head to be a little bit higher relative to the scope, than a bolt gun does. So you generally want to mount the scope a little higher on an AR. But it's a very personal thing - some people like their scopes higher than others do. The "proper" height is one that lets you feel comfortable behind it with a good cheek weld, and is high enough that the bell on the front end of the scope clears the top of the receiver and handguards. The receiver you have might work just fine for you. I'd suggest picking up a cheap set of standard Weaver-type scope rings, probably the "low" version, and mount your scope in them on your existing rail, and see how it works. If it's too high then you might have to have a gunsmith change out the upper receiver to a standard flattop one. Weaver, Burris, Redfield, and others make them, ranging in price from about $30 on up, although you could probably find a used set for less at a gun show. If it does work, then you have the option of replacing the cheap rings with a more expensive set if you feel you need to. Personally, I've never had any problem with even cheap rings returning to zero (after mounting, zeroing, and then removing the scope), as long as tighten the screws good. If you're not planning on taking the scope off after you get it zeroed, then return-to-zero isn't an issue. Also, the 20 MOA rails that you hear talked about are for <b>really</b> long range shooting, like out past 800 yards. They build a slight slope into the base itself, effectively pointing the scope down just slightly. Most scopes only have a limited amount of elevation adjustment range, and when you start trying to shoot targets way out there, you can run out of elevation and have to hold over, which is detrimental to accuracy. The ramped base allows you to zero your scope (at short range) at a lower than normal elevation setting, leaving you with more upward adjustment range for long distance. But for 600 yards with an AR, a standard base is fine, you don't need the ramped one. Any normal scope has plenty of elevation range for 600 yards. |
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Thank you very much Fairweather, I did mount the scope to the rail with a set of "cheap" rings and tested it on Saturday, I only had available a 25 yard range to do this but at least I was able to see that the medium height rings work fine for me and that there's plenty of adjustment there in either direction.
What I could use help with is the eye relief on he scope but seems that the LaRue mount that addresses that issue might be higher than medium height rings? |
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I think the Larue lt-104 and lt-139 put the centerline about 1.5" above the rail, which is about perfect for a normal flat-top.
Badger standard rings have a centerline at .823", their ultra-high alloy goes to 1.4". If I were you, I would look for the shortest rings that keep the objective of the scope from dinging your handguard/rail, and mount the scope as far forward in those rings as possible. ETA: DPMS makes (or made) an extended rail version of that upper to solve exactly your problem... but I don't see anyplace where you can order just the extension. Here's the upper available at midway: dpms extended rail upper receiver That is the whole receiver though. Maybe you could call DPMS and see if they will sell the extension alone. |
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Quoted: Thank you very much Fairweather, I did mount the scope to the rail with a set of "cheap" rings and tested it on Saturday, I only had available a 25 yard range to do this but at least I was able to see that the medium height rings work fine for me and that there's plenty of adjustment there in either direction. What I could use help with is the eye relief on he scope but seems that the LaRue mount that addresses that issue might be higher than medium height rings? That would be my guess, but a phone call or email to Larue with the type of ring you're using now might answer it. I assume you've tried mounting the rings farther forward on the base, and moving the scope as far forward as possible within the rings? Maybe experimenting with the spacing of the rings (moving them closer together or further apart to allow the scope to sit farther forward)? A lot of it depends on the configuration of the scope - where the turret housing is, how long the eyepiece is, and the spacing between the eyepiece and turrets and between the turrets and the front bell. Another alternative might be to get a simple riser and clamp it on the front part of your existing base, then get the lowest set of rings you can find and put the scope in them on top of the riser. Sort of a homemade cantilever mount. It might be too high for comfort even with the low rings, though. |
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A scout rail should solve your problems..................like THIS ONE
I'm pretty sure you can find 'em cheaper just this was the first one I found. |
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Quoted: A scout rail should solve your problems..................like THIS ONE I'm pretty sure you can find 'em cheaper just this was the first one I found. I have one I got from Cheaper than Gold for about $30.00....works fine. |
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