Interest in MCX adaptor for AR-15 lower ? - Page 2

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[ARCHIVED THREAD] - Interest in MCX adaptor for AR-15 lower ? (Page 2 of 2)

Posted: 4/17/2018 5:39:48 PM EDT

[#1]

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Quoted:
Now in stock at the Sig store! And my request to be notified has not yet been received.

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Same. Went ahead and ordered one for one of my SBR lowers. I intend to attach my Rattler upper to it, but, then again, I really like the Rattler lower w/the collapsible brace.

Posted: 4/17/2018 10:07:56 PM EDT

[#2]

Quote History

Quoted:
Now in stock at the Sig store! And my request to be notified has not yet been received.

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I never got an email either. Thank you for posting that they were up!

Posted: 4/17/2018 11:11:55 PM EDT

[#3]

Ordered one. I also never got the in stock notice.

My prototype adaptor doesn't have the qd swivel hole like it shown at the SIG store.

Thanks for the heads up on it.

Posted: 4/18/2018 5:18:52 AM EDT

[#4]

And... now out of stock. Damn.

Posted: 4/18/2018 2:38:36 PM EDT

[#5]

This adapter will not work with standard AR uppers correct? What about side chargers?

Posted: 4/18/2018 2:55:00 PM EDT

[#6]

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Quoted:
This adapter will not work with standard AR uppers correct? What about side chargers?

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A true "standard" AR upper will need a receiver extension ("buffer tube") in order to function. Side-charging AR uppers still use the receiver extension to function unless they've been significantly redesigned to not use the standard AR buffer/action spring design. As this adapter deletes the receiver extension, it absolutely will not work with a standard AR upper.

~Augee

Posted: 4/18/2018 3:13:27 PM EDT

[#7]

Quote History

Quoted:

A true "standard" AR upper will need a receiver extension ("buffer tube") in order to function. Side-charging AR uppers still use the receiver extension to function unless they've been significantly redesigned to not use the standard AR buffer/action spring design. As this adapter deletes the receiver extension, it absolutely will not work with a standard AR upper.

~Augee

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I was just looking at physically working with a standard AR upper and standard charging handle....like for an AR-22 build.

Posted: 4/18/2018 3:32:06 PM EDT

[#8]

With a 22 conversion kit it should work. Those kits don't use the buffer tube.

Posted: 4/18/2018 6:15:22 PM EDT

[#9]

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Quoted:
With a 22 conversion kit it should work. Those kits don't use the buffer tube.

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The standard charging handle from a regular AR upper would interfere with the adapter.

Posted: 4/18/2018 7:28:54 PM EDT

[#10]

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Quoted:

The standard charging handle from a regular AR upper would interfere with the adapter.

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From the pics that seemed to me like what would happen... Thanks!

Posted: 4/21/2018 10:35:31 PM EDT

[#11]

FYI.... Back in stock.

Posted: 4/22/2018 12:26:31 PM EDT

[#12]

Quote History

Quoted:
FYI.... Back in stock.

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Thanks for the heads up!

Posted: 4/27/2018 3:49:47 PM EDT

[#13]

Well I should be happy that I was able to score one but,,,,,

$10 shipping and they send it Smart Post

Two weeks to get here.

For the same $ they could have sent it USPS and I would already be shooting.

Anyone who is not familiar with Smart Post, it is the absolute worst. That is the reason I won't buy from Brownells anymore.
At least with Brownells thay don't charge for the crap shipping.

Posted: 7/28/2018 5:55:22 PM EDT

[#14]

I visited the KNS booth today at the TRIGGRCON trade show and found one of these: https://www.knsprecisioninc.com/product/ar-mcx-stock-adapter/

The KNS product rep stated that a AR charging handle on an AR upper will clear its adapter. My goal is to use a Sig Skeleton Stock on an AR-22LR SBR build. The Sig MCX adapter will not allow the use of an AR charging handle....but the KNS adapter WILL allow the use of a standard AR charging handle...so very happy that I was able to find this adapter.

Here are some pics of the KNS and the Sig adapters:

Posted: 8/2/2018 6:38:53 PM EDT

[#15]

Ended up getting the KNS stock adapter in today and installed it. I'm largely happy with it, but the thing doesn't capture the takedown pin and spring and because of the boss you can't install the plate. I know my lower is threaded for that hole, but I don't have any of the stupid tiny set screws.

Posted: 8/6/2018 1:09:06 PM EDT

[#16]

Quote History

Quoted:
Ended up getting the KNS stock adapter in today and installed it. I'm largely happy with it, but the thing doesn't capture the takedown pin and spring and because of the boss you can't install the plate. I know my lower is threaded for that hole, but I don't have any of the stupid tiny set screws.

https://i.imgur.com/UqZQa95.jpg

https://i.imgur.com/DNq652Z.jpg

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I'm a big fan of KNS, but that's just freaking dumb to not cover the takedown detent spring hole.

Posted: 8/6/2018 8:28:12 PM EDT

[#17]

Quote History

Quoted:
I'm a big fan of KNS, but that's just freaking dumb to not cover the takedown detent spring hole.

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Quote History

Quoted:

Quoted:
Ended up getting the KNS stock adapter in today and installed it. I'm largely happy with it, but the thing doesn't capture the takedown pin and spring and because of the boss you can't install the plate. I know my lower is threaded for that hole, but I don't have any of the stupid tiny set screws.

https://i.imgur.com/UqZQa95.jpg

https://i.imgur.com/DNq652Z.jpg

I'm a big fan of KNS, but that's just freaking dumb to not cover the takedown detent spring hole.

Yeah thats really weird.

Does the KNS attachment-adapter have a silicon buffer portion on the inside?

I wouldn't be able to use my SHF KES stock with that set-up (Have to remove the screw from the INSIDE of the receiver to tighten the adapter plate!)

The attaching instructions for the SHF KES stock says that without that buffer portion the MCX will not operate reliably.

Hmmm... I will wait for KNS to release the Mod 2 .

~Will

Posted: 8/8/2018 11:07:26 AM EDT

[#18]

Quote History

Quoted:

Does the KNS attachment-adapter have a silicon buffer portion on the inside?

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Nope, it's just a flat plate and the bolt-touching surface extends further into the buffer tower than the hollow MCX adapter that Sig made. The plug actually partially covers the buffer retaining pin hole. If you're looking to use an MCX upper with the AR lower I'm not sure the bolt would travel far enough back to chamber (though I haven't tried and I'm at work), but I'm positive the adapter is not tall enough to cover the recoil spring plate.

Now that I got some screws it's perfect for a .22! I may even look at an ARAK upper for this.

Posted: 9/2/2018 3:47:33 PM EDT

[#19]

Quote History

Quoted:
Ended up getting the KNS stock adapter in today and installed it. I'm largely happy with it, but the thing doesn't capture the takedown pin and spring and because of the boss you can't install the plate. I know my lower is threaded for that hole, but I don't have any of the stupid tiny set screws.

https://i.imgur.com/UqZQa95.jpg

https://i.imgur.com/DNq652Z.jpg

View Quote

After I posted my check fit pics on a spare lower I had laying around I went ahead and installed the adapter on my SBR lower and I ran into a couple of issues. One issue was what @RageAgainstTheVM posted regarding the takedown spring/detent, and the other is that the threaded portion of the adapter was a little too tight for my Spikes Tactical lower. I contacted KNS regarding these two issues and they sent me a new threaded portion of the adapter and one of their Enhanced Takedown Push Button pins. I think KNS is gonna be updating the railed portion of the adapter so it covers up the spring/detent hole.

@RageAgainstTheVM what size screws did you get for the lower? I also realized that my lower also has a threaded hole for the rear takedown spring/detent.

Here are some pics of the KNS adapter on my 22LR build with the Sig Skeleton Stock:

Posted: 9/3/2018 6:17:31 PM EDT

[#20]

Quote History

Quoted:

...One issue was what @RageAgainstTheVM posted regarding the takedown spring/detent, and the other is that the threaded portion of the adapter was a little too tight for my Spikes Tactical lower....

@RageAgainstTheVM what size screws did you get for the lower? I also realized that my lower also has a threaded hole for the rear takedown spring/detent.

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For the tightness on a Spike's: I had the same issue. I found that with a little Aeroshell grease and using the rail adapter like a key & boss (stick the rail into the threaded plug and use it to turn) I was able to screw the thing into my lower.

As for the screws, I used 4-40 x 1/8" screws from Amazon. I see the listing I used no longer sells these lengths, but either look for another listing or you can probably get away with the 3/16 or 3/32 screws: https://www.amazon.com/gp/product/B072MBLJ9C/

Posted: 9/3/2018 9:46:44 PM EDT

[#21]

I want three. Got 3 MCX uppers/

[ARCHIVED THREAD] - Interest in MCX adaptor for AR-15 lower ? (Page 2 of 2)

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