ok try this one

6 guns are not enough for anybody who loves pipes and powder but I dont think that is the right question...
One gun. No interchanging barrels, just one gun. long gun, pistol, shotgun or black powder. what would you choose?
One thing that I wondered about in the previous post is the fact that the question was kind of vague..
If it were a survival situation I think anybody would pick a round that was available. But then who are we trying to defend against?
Like Versifier said .308 is the most obvious.
I kept thinking it was a hard question and one I didnt want to extrapolate on to much.
If you were the average Joe and could afford only one gun in a stable economy maybe the above still applies.
In a war zone picking bullets off your enemy would not apply.
I'm glad I'm fat and happy and can sit behind a keyboard and smack nostalgic about things I know nothing about.
Anyway, 1 gun. I guess it would be the most versatile gun people who really know what they are talking about would pick.
The most available round.
.308