I'd like to get an AR15 that is chambered in 22LR to plink and train with.But don't want a plastic gun.Not putting down the S&W 15-22,it's a fun shooter,but not for me.I want aluminum receivers.Not a conversion,because I don't want to shoot 22lr through my colt barrels.
I've been looking on a certain gun store website which offered a CMMG mil spec m4 in 22lr for $650
Considerably higher priced than the S&W AR15/22.But supposedly like a real AR.
I called CMMG and they told me the rifle reciever was a CMMG aluminum lower,same as is used for their 5.56.Upper is an aluminum 22lr upper.
To my understanding it's a CMMG AR 15 W/a 22lr upper.
Before I buy,I'd like to know the opinion of anyone whom has seen and handled one,shot one or owns one.Not the opinion of a guy who is guessing..
Thanks in advance.  
J

I've got a complete upper from CMMG with the phospate bolt and use gray CMMG and BDM mags.  I also have the same 16" style M-4 barrel and phophate bolt in a DPMS upper where I changed out a DPMS Gen I barrel.  Both have been as reliable as any 22 can be.  Both are accurate enough for me but I rarely shoot these two uppers for groups.  I generally shoot steel targets or paper man size silohettes for CQB training.  The CMMG lower is a mil spec lower and can be used with any centerfire upper but will be stamped caliber 22 LR or Multi Cal..  I am using a CMMG lower with the complete upper I purchased but my lower says 223/5.56.

I say if you can live with the Price of the complete 22 LR AR-15 buy it, the price doesn't sount to bad.  I also prefer the aluminum receivers for dedicated 22LR AR-15's compared to the 15-22.

@VASCAR2
Thanks for your input.Just what I wanted to hear.I just secured it on a 6 mo layaway.I'll probably have it sooner,all depends on bussiness.
Anyway,I wanted a real AR  lower that is aluminum and although I will leave it as a dedicated 22lr,I still want the option to be able to change out the upper to.556
My buddy's son has the S&W 15/22.Although it's fun,I don't want all that plastic.My buddy has a CMMG 22lr conversion kit (bolt and 3 mags).but I don't want to shoot 22lr through my Colt or Armalite 1/7 barrels.
I need something dedicated and I don't want plastic .This sounds like the ticket!

What difference does the lower caliber marking make?

None, as far as I'm concerned but some people prefer the lower be specifically marked to match the cartridge/caliber of the upper.  It is usually a sign of a home built rifle if the lower cartridge markings don't match the upper.   I am more curious about specific parts than the actual upper and lower receiver that are generic forged/machined parts.  As far as I'm concerned the barrel/bolt and trigger (FCG) are the most important components of an AR-15.  Most other parts are personal choice as long as the materials and quality control are good.   The heart of any AR-15 is a good barrel, good trigger, good sights/optic and reliable magazines.  The shooter is responsible for the ammo and skill.

I have an Armalite AR15  5.56 defender.The lower reciever is stamped "Cal. Multi".
Doesn't bother me one bit.Great rifle!

Also look at building one with TACCOM parts.  

MAHA

I use a CMMG complete upper and swap it onto one of my lowers. Works great

^What he said. I have one SBR stamped lower and six different uppers, three 5.56, one 300BLK, one 9mm, and one .22LR. So for one $200 stamp I have essentially six SBR's.

I've owned their 22s. Factory complete. They are great. Only company (to my knowledge) with only ONE plastic part (comparing a 556/223 ar to the cmmg 22). That would be the charging handle! It still works great. My first one was an early production run. The only problem I had with it. MAGPUL mags fit was a little tight and they would not drop free. USGI mags had no issues. I also had their 5.56 and 9mm lowers. All are the same forgings with different nomenclature.

You can't go wrong.

While mine have gone to family (kids grow up fast). I still run home rolled cmmg uppers on two sbrs. One is a 4.5 the other a 9".