It's been a couple of years since I pondered the one gun scenario. For the purpose of this thread I'd like to assume that it's actually one rifle but also one hangun, and one shotgun - I think that changes the perspective some.
I opened the safe and looked over the lifetime collection thinking about each rifle chronologically; Hawken .50, Ruger 10-22, Winchester '94 30-30, 1917 (sporterized), 1903-A3, Garand, M1 Carbine, SKS, M1A, FR8, WASR10 (AK47), AR15. They all have to go except one...
We all know what pistols are for. Having a slug capable 12 gauge takes care of 25 to 100 yard zone quite well, so the carbines are sort of overlapped there - goodbye 10-22, '94, M1 Carbine, FR8, AK47, and the SKS (my favorite shooter in this group and actually more rifle than carbine, but it's questionable beyond 200 yds).
Blackpowder is great fun to shoot, but I can let the Hawken go with minimal angst, although if the ammo crunch gets worse...hmmm.
There's a lot to be said about the virtues of a good bolt action, and has in fact already been said in this thread. If I had a sweet .300 win mag or tactical .338 Lapua in the stable it would be the probable choice based on capability (maximum terminal performance - accuracy/energy/distance) but I don't have one and probably never will. I'm kind of a battle rifle junkie, in case you didn't notice.
My lump of dead or dying cells that passes for a brain says "semi-auto". This is where it gets really tough. Shooting the Garand is a religious experience.
'06 is a great cartridge, but it's full spectrum of capability is limited by Garand friendly loads. Heavy, relatively low capacity, come get me I'm dry "ping" alarm... Damn! I'm really gonna miss the M1.
So I'm down to the AR15 (pre-ban A2) or the M1A. In a SHTF, zombies coming, bug-out scenario - AR wins. Light, fast and easy handling, robust, accurate, compact ammo, high cap and can pour it on (even as a semi-auto) out to 500 yards which compensates for a cartridge appropriate for meat puppets under 50 lbs (IMO).
BUT - my little world as it exists has nothing to do with combat and I hunt for my chow at the supermarket. I love firearms for their aesthetic beauty, precision, and machine-as-art quality. Beauty is in the eye of the beholder and this beholder considers the M1A one of the most beautiful and precise machines in my safe. That's my one rifle.
