Your One Gun

[Ironbear]

If for more rural/woods survival, a Savage 24 in .22lr/20g or a similar good quality drilling in either .22lr/20g or 22lr/12g.

[LePetomane]

S&W 686 Plus. .357 Mag is one of the most flexible calibers and the 686 is easy to shoot.

My choice as well except I own the six shooter. A fine handgun.

[Holland&Holland]

Nope, been scientifically proven that man can not live with one gun alone. Your heart has 4 chambers so...

basic needs are:

a .22 (can't go wrong with a 10/22 here)
12 gauge shot gun (870 pump would fit that bill well)
Basic handgun for self defense and carry (Glock 19, though I could argue for a .357 revo too here)
Bolt action rifle (rem 700 in .308 or equivalent)

[Bearcatrp]

Near impossible to choose just 1 gun but if I had to, then my 308 pistol build I did not to long ago. 10.5 inch barrel with sig brace. But realistically, am presuming your thinking of a SHTF scenario in which my pistol strapped to my vest, my short 12 gauge strapped to my back and carrying my 308 shorty.

[Rodentman]

S&W 327 SRR8:

.357 mag
8 shot
reliable
moon clips for faster reloading
rails for scope and light

Of course picking one is not an easy choice.

[Sammichman]

I think in a survival mode I have to go rounds in Mags so my CZ75 gets the nod for a Pistol and my New Ruger AR get the nod in a Rifle, Naturally for incoming Russian or North Korean ICBMs i trust my 375HH to save the world