I've found a lot of inexperienced shooters asking on the corners of the internet if a Smith and Wesson 15 22 can be converted to shoot .223 and most people's responces go a lot like "no, the pressures wouldn't hold" and "the buffer tube is fake"

my responce is "well no duh I can't shoot .223 out of a 22 LR"

I want to know if I buy a .223 upper, and an actual buffer tube, will it work at this point??? is it even possible to change the buffer tube?

and please people.... Don't answer "no, you'd need a buffer spring" .......

No, the M&P 15-22 lower is built to slightly different measurements to keep a 5.56 upper from fitting.

Nope it won't work, the lower won't even mate properly with a real milspec upper.

NO WAY on the planet can you make that conversion. They are two completely different weapon systems and NOTHING will match and be even close to safe for shooting. You want a 22 buy a 22. You want a 5.56/223 buy a 5.56/223.

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THIS WE'LL DEFEND ΜΟΛΩΝ ΛΑΒΕ

The M&P 15-22 only mimics the exterior appearance of a centerfire AR-15. The dimensional specs of the lower are incompatible with a milspec dimension upper receiver.

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-John

No. Unlike an AR, the 1522 receiver and receiver extension tube are one piece of molded plastic. Even of you were to saw off the 1522 reciever extension tube it would be a hopeless endeavor to modify it for a working .223 buffer. However, some guys have chopped it off and and modified the receiver to allow it to accept an extension tube just to change stocks.

Nope won't happen. If you want to do anything like this you will need to buy a AR15 then buy a dedicated .22 upper for it. Just the reverse.

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Psalm 23:4

The opposite works nicely (albeit costs a few scheckles more)
Here in my recent build of a S&W M&P 15 lower with Chiappa upper.

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Dave

Dave.
That is an m&p 15 .223 lower with a 22l upper ?

Thank you

Yes, it is. That is a dedicated .22lr upper, made to work on standard lowers.

That is awesome. Exactly what I am looking to build. You say made to fit a standard lower. Did you have to modify the upper assembly ? Or do I just need to be sure and purchase the proper 22lr upper ?
Thank you

You just need to make sure the upper is of mil spec dimensions so that it will mate with your lower.

Thank you very much

Johnnh54, I have a CMMG .22 LR upper I use on various lowers. Works fine with a S&W MP15 lower, though it is usually on a Brand X lower.



This is the CMMG upper shortly after I received it. I changed out the oversized "Glacier Guard" handguard for a similar looking but smaller CAR handguard. Other than that it's out of the box. The optic is an EOTech and and one of my suppressors on it.

The CMMG, like most dedicated .22 LR conversion uppers, requires a rounded, not notched, hammer. The S&W MP15 has a rounded hammer. The Brand X lower in this pic needed the notched hammer swapped out to work.

The magazine is a factory CMMG, but the Black Dog magazines work better. I've heard that MP15-22 mags will work, but this really needs the mags made specifically for AR15 lowers.

So far it has been reliable with all supersonic ammo and with most subsonic.

The barrel is .222 bore because it is specifically made for the .22 LR, so accuracy is better than using a chamber insert style conversion kit as it would use the .224" barrel.

The upper receiver is genuine AR15, so it is metal, not plastic like some other .22 uppers.

This is a fun conversion. CMMG makes several different styles of dedicate .22 LR uppers. Several carbines and a 20" rifle.

I have a similar setup.... whole rifle from CMMG. I added a Better-Mag adapter to mine so that it could use M&P 15-22 magazines. I did this for two reasons: 1. We already had a 15-22 and magazines were available locally, and 2. The Better-Mag adapter gives the rifle the bolt hold open feature, even with the magazine removed.

Better Mag adapter? Thanks, will look into that.

Here's the link. Works great in my rifle!

Better-Mag S&W(R) .22 Rimfire Magazine Adaptor

Very nice. I appreciate all the info. I'll be putting it to use very soon.