I just picked up a Colt AR6720 which is compatible with 223REM/5.56NATO.  This is my first AR-15.  Any feedback as to which is better?  I know this is a rookie question, but my local ammo supplier is out of 5,56, but has tons of 223.  

Thanks!

Sometimes what you can get is just as important.

I reality, your bbl twist will determine the length (weight) range your rig is intended to use. A 1:7 tends to run the longer (heavier) bullets, while those 1:12 twists are intended for the lightweight (short) varmint rounds.

The small difference between 223 and 556 ammo is that the 556 is loaded to a slightly higher pressure.

You should run a few different brands and types to see what your rig likes. If your bbl is a 1:9 or 1:7 twist, your practical bullet weight range will be in that 62, 69, 75, 77 range. Some rigs will handle the 55 grain loads just fine at 1:7 and some won't. You will just have to try those too.

It is good to try a little 55 grain M193 ammo since it can be common and inexpensive.

There are several sticky notes at the top of the sections that have good basic information too. You should read all those too.

Welcome to the affliction...  Safe shooting.

If .223 is what is available then by all means use it. Generally speaking .223 loads will offer better accuracy than M193 or M855 (both 5.56 loads).

.223 will usually be more expensive than most 5.56.

There are exceptions to both of the above statements.

Just get some ammo and start enjoying your rifle!

What they said.

Generally you can find Federal XM193 (55 grain fmj) pretty cheap at Walmart and it makes good plinking ammo. But my 6920 shoots the American Eagle green tip (62 grain fmj) a bit more accurately. It's also pretty resonably priced at Walmart.

Thanks for the gouge folks...really appreciate it!

How is Federal Munitions 223 and 5.56 ammo?

You will find that all of it goes when you pull the trigger.

What do you want to do with your rifle ?...bulk ammo is good for ( IMHO ) blasting and rifle handling practice.... ( run n' gun )

For accuracy and bench work.... I suggest you buy some of all you can find, and try them all out. There can be surprising accuracy differences in alike ammo brands.... not to mention amongst the rifle brands.

Generally speaking, for inexpensive accurate 100-200 yard ammo... Fed. Tipped Varmint 50gr is VERY hard to beat.....

BUT IMHO it is not suitable for SD, there are FAR better bullets available for that.

This is a good deal for a respected ammo online....http://www.targetsportsusa.com/wolf-gold-223-remington-ammo-55-grain-fmj-wg59-p-4316.aspx

If you order a case shipping is free.

Sorry...I meant Freedom Munitions:)

Do what you want, but with current prices the way they are there is no reason to take a chance with ammo that has a track record of causing issues.

This. Especially when The Armory has Wolf Gold (brass-cased, accurate & very near to 5.56 velocities) for $299/case shipped w/free PA120 or .50 ammo can:
http://www.the-armory.com/shopsite_sc/store/html/223_ammunition.html
Tomac

This is a hell of a deal, and great ammo for your colt.

http://massammo.com/federal-5-56x45-nato-223-rem-xm193-420-round-ammo-can.html


Txl