coyotex,
You know I've been saying that ever since a friend of mine gave me a live 5.7 x 28 cartridge and it is setting in front of me right now on my computer desk. I keep picking it up and saying the same thing as you....this would be a great fox round. A little more than a 22 mag. but not blow them up like a 223 rem.
Only difference is, I would want it in a bolt gun since we can't use semi auto rifles in Pennsylvania for hunting. (bummer).
And as far as the other guy saying short rounds have a feeding problem in AR platform type rifles...how do you explain the S&W M&P 15-22 that shoots 22 long rifles. Of which I have one.
They just necked down the magazine to the 22 cartridge.