Geissele mk8 compatibility with billet uppers

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[ARCHIVED THREAD] - Geissele mk8 compatibility with billet uppers

Posted: 5/26/2017 9:29:04 PM EDT

It's my understanding that the anti-rotation tabs can interfere with some of the cuts and designs of billet uppers. Does anyone know if cmt billet uppers will work? Can't seem to find anything.

Posted: 5/26/2017 9:48:15 PM EDT

[#1]

Quoted:
It's my understanding that the anti-rotation tabs can interfere with some of the cuts and designs of billet uppers. Does anyone know if cmt billet uppers will work? Can't seem to find anything.

View Quote

In an old post, a Geissele rep stated that, the rails were designed for forged upper. For billet, some material on the tab must be removed.

Posted: 5/26/2017 11:29:52 PM EDT

[#2]

My mk4 fit just fine to my Vltor mur upper receiver without a problem

Posted: 5/27/2017 9:59:29 AM EDT

[#3]

They very recently redesigned the anti rotation tabs. They are no longer set screw based at the 3 and 9 o'clock but rather fixed, no set screw tabs at the 1 and 11 o'clock (roughly). They haven't updated all the pics on their web site and inventory doesn't appear to be 100% current with all vendors just yet either.

I am guessing that the new anti rotation tabs may be more compatible with a wider variety of uppers. Personally?, I like the set screw ones better, but I don't use billet uppers either.

Posted: 5/27/2017 10:11:29 AM EDT

[#4]

Quote History

Quoted:
My mk4 fit just fine to my Vltor mur upper receiver without a problem

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This. Love both of mine

Posted: 5/27/2017 3:23:54 PM EDT

[#5]

Quote History

Quoted:
They very recently redesigned the anti rotation tabs. They are no longer set screw based at the 3 and 9 o'clock but rather fixed, no set screw tabs at the 1 and 11 o'clock (roughly). They haven't updated all the pics on their web site and inventory doesn't appear to be 100% current with all vendors just yet either.

I am guessing that the new anti rotation tabs may be more compatible with a wider variety of uppers. Personally?, I like the set screw ones better, but I don't use billet uppers either.

View Quote

That's the mk13&14 that changed the anti-rotation tabs

Posted: 5/27/2017 9:47:37 PM EDT

[#6]

Fits perfectly on my CMT

Posted: 5/28/2017 12:51:00 AM EDT

[#7]

Quote History

Quoted:

That's the mk13&14 that changed the anti-rotation tabs

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No it's not just those. Look at the pics for the Mk4

https://geissele.com/super-modular-rail-mk4-m-lok-607.html

Posted: 5/28/2017 8:17:25 AM EDT

[#8]

Quote History

Quoted:

No it's not just those. Look at the pics for the Mk4

https://geissele.com/super-modular-rail-mk4-m-lok-607.html

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I stand partially corrected. The mk8 still looks like it has the old style tabs though

Posted: 5/28/2017 8:18:49 AM EDT

[#9]

Double tap

Posted: 5/28/2017 1:40:27 PM EDT

[#10]

Quote History

Quoted:
Fits perfectly on my CMT

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Posted: 5/30/2017 12:57:34 AM EDT

[#11]

Quote History

Quoted:

I stand partially corrected. The mk8 still looks like it has the old style tabs though

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Call/email them and ask about the changes and they will tell you all new made rails are now non set screw. There are probably some set screws still in the supply chain for now.

Posted: 5/30/2017 5:30:59 PM EDT

[#12]

I just got a MK8 today and was surprised to find out it would NOT work with my SMOAS billet upper.

Looks like I am in the market for a MK14 rail now.

Posted: 6/2/2017 7:19:49 AM EDT

[#13]

Quote History

Quoted:
I just got a MK8 today and was surprised to find out it would NOT work with my SMOAS billet upper.

http://i.imgur.com/96j2Oj5.jpg
http://i.imgur.com/B3Age0Z.jpg

Looks like I am in the market for a MK14 rail now.

View Quote

That rail has the old style anti-rotation tabs.

You may not be interested, but you can modify the rail tabs to work with your billet upper. I had to do it with a 15"Mk4 on a Mega billet upper. If you've got a dremel tool, it's about a 30 minute fix.

Posted: 6/2/2017 1:07:00 PM EDT

[#14]

Quote History

Quoted:
I just got a MK8 today and was surprised to find out it would NOT work with my SMOAS billet upper.

Looks like I am in the market for a MK14 rail now.

View Quote

What size is this one?

[ARCHIVED THREAD] - Geissele mk8 compatibility with billet uppers

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