7.62 x 25 Uppers?

I think this would make a good 14-16 inch barreled upper. I saw some discussion on AR15.com but I didn't see any one that has any thing available. It may not be feasable but looks interesting.

I have a CZ52 and like the fairly fast 7.62 round that has pretty good penetration.

They also mentioned a 10mm upper. It may be a little more mainstream but I'd still like a 7.62.

CW

that would make an interesting SMG.

I think the key to an other caliber upper is the availability of clean ammo.