[tomdashle]

I've only shot AR's that are calibered .223.

Do any AR's shoot UN standard or AK 7.62x39 rounds?

[bkt]

Sure! DPMS makes some and you might be able to find other manufacturers that also offer them.

Traditionally, the AR-15 and similar fire NATO 5.56mm which is very similar to Remington .223. The AR-10 fires a 7.62x51 (.308) round which might be more to your liking. It is functionally similar to the AR15 but heavier, of course.

[ChrisMoore]

I have a both a Stag Arms in 5.56 / .233 and a Barrett in 6.8. The 6.8 is awesome but it's hard to find ammo for and it's expensive when you do find it. The ballistics on the 6.8 are outstanding though! It has great knock down power and superior accuracy to that of the 5.56 / .223.

[Bidah]

Let me see if I can remember them all..

On a standard 5.56 lower, with an upper change you can get:
.50 Beowolf
450 Bushmaster (just released)
6.5 Grendel (awesome long range round0
6.8 SPC (mentioned above)
7.62x39
9mm
.45ACP
.300 Whisper

That should be close to most of them.

[AR Hammer]

Forgot one or two of my favorites, .22 LR and .22 WMR.

I understand there is someone making .17 rim uppers now also...

[FALPhil]

Originally Posted by tomdashle

Do any AR's shoot UN standard or AK 7.62x39 rounds?

The UN has standards???

[ranger_sxt]

Originally Posted by Bidah

Let me see if I can remember them all..

On a standard 5.56 lower, with an upper change you can get:
.50 Beowolf
450 Bushmaster (just released)
6.5 Grendel (awesome long range round0
6.8 SPC (mentioned above)
7.62x39
9mm
.45ACP
.300 Whisper

That should be close to most of them.

You forgot:
.458 SOCOM
.24 Ghengis (5.45x39 with a different name)
.499 Leitner-Wise

And you need to get a dedicated lower to shoot the .45ACP

[AR Hammer]

Let's stick to 'SAMMI' rounds here! You are making my head hurt...

Anyone remember the .222 AR's from the factory?
I used to smack ground hogs with them WAY back...
--------

My .45 upper does NOT need a dedicated lower.
I know the ones using some of the double stack mags do.

[bkt]

Originally Posted by FALPhil

The UN has standards???

I think he meant NATO. The the UN has no standards whatsoever.

[Bidah]

Yeah, those .222's were for countries like in South America where citizens cannot own anything made is a military caliber. Ruger sold a lot of Mini-14's down there in that caliber.

-Bidah