Is anyone just neck sizing for the AR-15

Don't do it. No one is neck sizing in the High Power crowd and these are the folks (including me) who are ringing the accuracy out of the AR platform. I've seen the aftermath of an out of battery firing, you don't want to be near one,ever.

At best you'll just have a lot of jams. At worst, you'll lose a finger or worse, in the event of an out of battery fire.

I wouldn't even do neck sizing for hunting ammo used in a bolt action. Imagine how stupid you would feel if the tophy of a lifetime is getting away because you can't chamber a round easily.

Save that for benchresting.

always full length resize.

Thanks for all the info

Is a standard full length die ok, or do you need a Small base-circle die to reliably feed in an AR?

For a standard Ar15 rifle and chamber (ie, not a Spacegun) I would recommend a small base. It's better to be safe than sorry.

How about the wylde chamber from RRA that is coming on my NM upper?

The wylde chamber is designed slightly on the large size to accept almost any 5.56/223 brass you can put in it. It does so quite well and accurately according to somethings I have read, so I would guess that standard 223 dies would work fine.

You will be pleased with your Rock River Micmac. Standard full length size dies will work, I've been around a LOT of AR's and never seen one that needed small base dies.

The reason I suggest the use of small base dies is because for some ARs you can not be sure if it has a Nato chamber or a 223. Yes there are differences, the Nato chamber is larger. The military designed it this way to allow the use of any manufactured ammo to work in the rifle and also allow room incase of dirt building up during combat. Now if your Ar15 has a different chamber, usually the SAAMI 223, your chamber will be slightly tight for using surplus 5.56 brass, therefore one should use small base dies to be on the safe side when firing in a rifle where the chamber specs are not quite known.

Actually, from what I've read, the dimensions of the chamber are identical. The difference is in the throat, which is longer on the 5.56. Another .223 chamber is the "Wylde" chamber, which is between the two in throat length.

To finish my thought (mind isn't working real fast this morning) I use standard Lee dies and full length resize for my RRA (Wylde). Haven't had a problem with LC or Winchester brass in a couple of thousand rounds. IMHO, small base dies aren't necessary and will reduce the life of your brass by overworking.