I'm looking at a Olympic Arms Gamestalker in 300 Olympic Super Short Magnum.  Anyone have any experience with it?  They claim near-.30-06 ballistics.  I would love a .30 in a compact AR-15 package.  I do 90% of my deer hunting from a tree stand.  They sell a Hornady reloading die for it, so ammo shouldn't be an issue.

Go to the link below on the Olympic Arms Owners Association forum.  It will have everything you're looking for.

http://www.oa2.org/forums/viewforum.php?f=66

I have one.  General perceptions:

1.  Yes, it will exceed 30-06 ballistics with 150 grain bullets (I have achieved 3200 fps in one load, 3000 fps performs better though).
2.  The factory HSM ammo is terrible (shoots patterns) out of my gun.
3.  You will have difficulty using many 165 grain and up size bullets due to magazine length restrictions.
4.  With handloading, I have been able to get acceptable accuracy for a 250 yard huting platform.