I would trim down the SHTF arsenal to fewer calibers to allow you to stock up on more ammo for each. Here are some comments on why each of them.
.22 lr = Marlin Golden 39A
* Rock solid reliability. Tube magazine for high capacity. If you get a good model out of the box, it should work for years without service. Also doesn't look intimidating (lever action). It looks like a good old cowboy gun, but is a great performer and deadly weapon.
9mm = Glock 17 with 17round mags
* Rock solid reliability. High capacity with the 9mm and great for personal protection. Great shooter to hand off to the wife or son. Nothing fancy, point and squeeze.
7.62 = Saiga Rifle
* Rock solid reliability. This is a nice caliber rifle for anything up to deer. Even in the standard configuration with 10round mags, you have a lot of firepower out to a solid 200 yards. Most shots will be well under. You can throw it down in the snow, mud, dirt or anywhere and it will still continue to run. Scope it if you like or run the irons.
12guage = Remington 870 with Deer Barrel and Long Goose Barrel
Bird Shot #6, Goose/Turkey Shot BB, Slugs & Buckshot
* Rock solid reliability. This is another great american firearm. With both barrels you have a gun for any season. This one gun would be enough to keep your family safe and fed for many years. Many accessories also available (high capacity magazine/pistol grip). Low cost.
Bottom line, you want reliable weapons for the SHTF situation. I have found that keeping bullets for more than these starts to get difficult. I generally don't have more than a box or two on hand for other guns. These are easy to stock up a few hundred rounds of each.