You obviously have your pistol and small game needs covered. Since you need a medium game-taker if you plan to survive off the land, the question becomes what is the territory like where you will hunt? 30-30 is a great brush gun, and with a scope will do 350 yards no problem. The round is also good through brush. However, a shotgun can cover these shots equally well out to 250 yards with a slug and give you bird-taking capabilities as well as buckshot for close deer and defense. So if you're going to add only one gun, I'd say a good-quality shotgun. If your game is farther away, say 400 yards plus, consider a scoped hunting rifle, but this is based on your terrain near your bunker.
“Malo periculosam, libertatem quam quietam servitutem." (I prefer the tumult of liberty to the quiet of servitude.). Thomas Jefferson
"All that is necessary for the triumph of evil is that good men do nothing."
-Edmund Burke, Loosely translated from Thoughts on the Cause of Present Discontents. (1770)