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Posted: 5/5/2009 6:40:37 PM EDT
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I recently purchased a 16" flat top upper with fixed front sight. I added the regular ARMS #40 BUIS. I am looking to add a 4.5-14x Burris scope and need recommendations for a scope riser mount.
Specifically: 1) One that raises the scope high enough so that the front sight is not an issue. 2) Raises it to clear the folding rear sight. 3) Fits on the remaining rail not taken by the ARMS 40. (I have seen some that look like they cover the whole rail on the receiver) 4) Preferably one-piece with built in rings. 5) Not Chicom but less than $150. I realize these topics are scattered throughout this forum but I think there should be some guys with this set-up and I'd like to hear their recommendations. Thanks. 
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Front sight won't be an issue with that mag range - it pretty much disappears into a shadow above 4x.
Clearing the ARMS 40 will be a problem, though - it's one of the highest flip-up BUIS out there, and not many mounts will clear it. When you do clear it, you're going to be up pretty high, and may have less than perfect cheek weld. You might want to sell or trade the ARMS 40 for a lower BUIS. Here's how to figure it out: - Measure the eyepiece diameter of your scope, with a flip cap if you're going to use one. Butler creek typically adds 0.1" to the diameter. - Divide that by 2, and add it to the height of your BUIS. The spec is 0.95" for the ARMS 40 (mine is 1.0"). That will give you the minimum mount centerline height you'll need to clear that BUIS with that scope. To tell what BUIS would fit if you decide to trade the ARMS 40, pick a mount, subtract half of your scope eyepiece diameter from the mount centerline, and that'll give you the tallest BUIS that will fit under it. Here's the Big List of AR15 one-piece mounts, including sections on rings and extended rails, and the centerline heights of most mounts: Big List of AR15 One-Piece Mounts And here's the height of many flip-up BUIS: ARMS 40 - 0.95" folded (mine is 1.00" even) YHM-9680 - 0.84" to the top of the windage knob, 0.74" to the top of the sight body Matech - 0.75" folded at the elevation adjustment, off to the side, 0.6" closer to center MI ERS - 0.75" folded GG&G MAD - 0.625" folded Magpul MBUS - 0.625" folded (not verified) ARMS 40L - 0.61" folded (mine is 0.59") Troy - 0.460" folded MI MCTAR-SPLP - .438" folded YHM QDS - 0.435" folded KAC 300m - 0.315" folded |
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Ah, gotcha! The ARMS 40 is one of the pieces of gear that got me started on this whole BUIS/mount data collection.
I bought one cheap on the EE some years ago, along with the Armalite mount, since both had very good reviews. They each worked fine, but not together. One thing lead to another... I have a half-dozen one-piece mounts of various sizes, and I haven't found any combination that the ARMS 40 will fit under (the LaRue LT-135 is probably tall enough with some scopes, but it's a special purpose mount). I can only use it on rifles with non-magnified sights like the Eotech, where there's enough room ahead of the BUIS for the entire optic. |
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