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Discussion Starter #1
Good day everyone and Merry Christmas!

I am looking for some suggestions on how to make a M&p 15-22 upper fit a Mil-Spec Ar lower?
I have done a ton of research but can not find any info... people are saying the take down pins don't line up, if so by how much? Up, down, right, left... how far are they offset? Is that the only thing that prevents a 15-22 upper to install on an Mil-Spec lower?

I really would like to modify a lower as I just ordered a 15-22 and don't like how the buffer tube is one piece with the lower, as I wanted to install an Ar sling adapter on to the end of the lower.

I know S&W did this on purpose so people don't throw a 5.56 upper on to the 15-22 lower which makes sense, tho I would like to have a regular Mil-Spec lower installed to my 15-22 upper. Can someone tell me all the modifications it will take?

Thanks in advance.
 

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I've owned a 15-22 since they first came out in 2009. Great rifle. Haven't seen anyone successfully mate an AR lower, though I have seen the question asked a zillion times.

I really would like to modify a lower as I just ordered a 15-22 and don't like how the buffer tube is one piece with the lower, as I wanted to install an Ar sling adapter on to the end of the lower.

Back in the day guys were using clamp-on style sling attachment point. Tacticool22 makes a QD clamp-on for the 15-22. https://www.tacticool22.com/product/ar10-ar15-ambidextrous-qd-single-point-sling-adapter-removable-swivel/

At one time the 15-22 Magpul Edition came with a QD sling point drilled and mounted into the receiver.

Good luck.
 

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Discussion Starter #3
Thanks for the quick reply! So what are all factors for the 15-22 upper not fitting a lower?
I watched a youtube video and the guy tried a swap and only mentioned the take down pins not lining up.

With some modifications to a mil-spec lower the take down pins holes could be manufactured in the spot they have to be for the 15-22 upper to sit right. Is this the only thing preventing a 15-22 upper to install on a mil-spec lower?

I really would have liked to get a metal lower instead of that polymer molded one piece construction.

I know 5.56 mags would also not fit into the 15-22 lower if someone were gonna try to swap a 5.56 on to the 15-22 lower, which would be plain stupid as the 15-22 lower is polymer, so I wonder if 15-22 mags would fit into a mil-spec lower.

Can someone post pictures of how a 15-22 would look on a mil-spec lower, how far are the holes off. Would magazine fit? Would trigger work, charging handle pull back possible?

I would try myself tho I am waiting for my 15-22 to arrive in the mail .
 

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If I remember correctly there is more to it than the pins not lining up. I believe the entire upper on the 15-22 is narrower than an AR upper
 

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Discussion Starter #6
You just need to purchase a 5.56 model and not ruin a firearm.
That is besides the point as I do not want a 5.56. I have a .223 rem for varmint hunting already, no use for a Semi in 5.56 Nato.
I would just like to upgrade the cheap polymer lower with a metal mil spec lower.

It would be nice to see some actual close up pics of someone setting a 15-22 upper on a mil-spec lower, so I understand why it would not fit. Everything can be made to fit with enough modification and I would like to know what one would have to modify on a mil-spec lower.

I suppose no one has ever tried hard enough as there is not much info online, people just say pins don't line up and then give up.
 

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I took a couple pics.

The first obvious difference is the front pivots. The 15-22 has a ton more material around the front pivot which won't allow the AR lower to get close enough to center to line up the pin. A Dremel could remedy that. The rear pivots appear about the same dimension. The spacing between pivots front to rear appears near identical. So.... if someone was to remove a bunch of material from the 15-22 front pivot I believe the two could be pinned together MAYBE. Whether or not the result would be working gun... no clue.

Answers to questions you didn't ask:

I've got over 40k rounds through my 15-22. It's as reliable at 40k as it was new. No worries about a polymer lower.

Most guys who want their AR lower on a rimfire upper is for training. They've got a bunch of money invested into a trigger and extras on their AR lower and that's what they want to train with. CMMG and Palmetto offer a variety of AR22 uppers.

In any event... good luck with your project.. but maybe think twice and forget about it. :D

Front pivots
IMG_0278.jpg

Rear pivots
IMG_0280.jpg

This pic is about useless, but the distance between pivots is near identical when seeing it in person.
IMG_0279.jpg

This is my CMMG dedicated upper. It will work with any of my AR lowers.
IMG_5484.jpg
 

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The 15-22 was made specifically so that the upper would not fit a standard lower. The magazine wells are totally different and won't match up under any circumstance, and as already mentioned the takedown pins are not located to match up either.
If you want to shoot the 22 LR out of an AR platform rifle, buy a standard AR-15, and then buy a 22 LR conversion kit that's available all over in the internet gun shops. A good conversion kit will cost a couple hundred dollars, and they now pretty much perform perfectly without any additional tuning needed.
 
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