I believe that the best weapon to use in a zombie appocolypse would be a silenced assault rifle. Your weapon must be silenced and have no lights. Sound and lights attract zombies there for i believe a silenced weapon with no lights would be best. An assault rifle is fast paced and can shoot farther than many weapons. Range matters!!! That is why I believe that a silenced assault rifle with no lights, not even a red dot sight, would be best in a zombie apocalypse.
I think it should be a .22 caliber hunting rifle simply because a) it has plenty of range, like you said b) it is the most plentiful type of ammo around. Plus there are multiple firearms that shoot .22 caliber rounds. That is my argument.
A .22 calibur hunting rifle, really? A .22 is weak and would take for ever to kill a zombie. You need a weapon that is strong and has plenty of range. It also needs to have good fire power. If it does'nt have all of these qualities then it would not make a good weapon for killing zombies. I still believe that it needs to either be a quiet weapon or have a silencer on it. You also need to take all the light away from the weapon as you can. As I said light and sound are two of the main things that attract a zombie.
If you can kill a full-grown deer with 1 shot of a .22, you can sure enough blow the brains out of a zombies skull. But it should be semi-automatic, not a bolt-action unless you're 50-60 yards away. But if it's just a few feet away, you should go with a semi-automatic, or you're dead. Now about the issue of light and sound, that cant really be fixed, unless you make a silencer yourself. Other than that, a .22 is your best bet in surviving a zombie apocalypse.
In my next and final argument I will state that a .22 hunting rifle would not be strong enough for a zombie apocalypse. I would use a slightly stronger weapon but not to much stronger because you do not want a weapon that is going to have a strong kick back. You want a weapon that is strong enough to kill easily but not so strong it will knock you back.
Back to my statement in which I said that you needed to have as little sound and light as possible. This is true for like I said, zombies are attracted to both sound and light.
Now to secondary pistols. A .44 magnum would be nice but, it is to loud. I am going to have to go with the .9mm pistol for it can kill and is quieter than most. It does not put off to much light either.
I would also have a hatchet or two for extra weaponry. You'll need it.
Here is a pretty cool video I found.