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Rifle Scopes Geissele Mount Question

Joemannnnn

Private
Full Member
Minuteman
Nov 16, 2017
30
6
Raleigh, NC
Hey Guys, I'm building a grendel AR15 and recently purchased a Gen 2 Razor 3x18 and a Geissele mount second hand as a package deal. Scope mount arrived today and looked larger than I expected. Turns out it is a AR10 hyper-extended version. It's partially my fault as I didn't know think about an AR10 variant. I had asked if there was any MOA, if it was setup on an AR, and if it allowed for proper eye relief and was satisfied with the answers and assumed it would work. So basically I have the 34mm, 0 moa, hyper extended, AR10 version

Any thoughts on how this will play out on the AR15? I don't have my upper handy and figured I'd get some opinions here.
 
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What's the part number on the side of the mount?

Part # 05-411

I've since gotten home and did some research. I was surprised there was an AR10 version as the rail is the same. The ar10 mount version's lugs spans 13 rail sections vs 7 on the ar15 version. The AR10 has a longer receiver, so this makes sense I suppose. It seems the ar10 versions have less forward extension beyond the mount's front lug. I believe the version I received to be the hyper extended version, but still only has about 2" beyond that front lug. Again, probably less extension since ar10s are longer and they assume the mount can be moved forward further.

Pic below attached to upper, still in the build process. It's too dark to go outside and try to test it, but i did put on my lower, to try and take a quick look. The scope hangs slightly off the back near charging handle, it will be close to working. I think about 3" of extension would be be ideal and the shorter base of the ar15 version to allow more wiggle room/adjustment on the receiver.

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That's about the same cantilever as the AR15 standard version. It won't hurt anything running the AR10 on a AR15, you'll never know the difference. It looks about right to where most usually end up but if for some reason you need more extensions then just sell it and buy whichever version you need.