Does anyone know of experimentation in this direction? Seems like a 6.8 SPC or 7.62x39 necked to .224 could get quite a lot more speed and performance from the AR platform.

Thoughts?

Not sure, but if you want the most powder capacity in the AR15 platform just do up a 223 WSM.

You can do a 22X39 Ackley. That would make it a 22PPC.
Butch

DTech offers a .22 DTI which is the 6.8spc necked down to .223.

Easier brass and magazine availability/price than the .223 WSSM and bolts are far more common.

223WSSM brass is a beech!
Butch

Yeah that is what I was thinking about the WSSM.

case capacity? HERE is your case capcity:

http://www.tactilite.com/index.php?...&option=com_virtuemart&Itemid=29

Scha-WING!

I have been wanting to play with a large capacity and faster 224 in an AR platform for a long time as well. Never could figure out why the 22x39 or 22SPC had not been done by one of the AR manufacturers. I could really dig one of these for coyote calling.