Coming back to caliber, true that there's no perfect one, as noted a 22 can be put together to be a tack driver (I know because I have one) it'll take more than one shot to the brainpan to drop a plod, lots of cases where the living(even more dependant on a one-piece damage free brain) keep right on trucking with a couple slugs in the cranium. Great if you have time and protection to line up your shot.
But.....you're in a dim, musty old garage looking for motoroil. Picking around the mess searching, you find yourself face to face with the former owner who wants nothing more than to eat your flesh, strip your bones and suck your brain out thru a crushed eye socket.
Pew! Pew-pew! ain't gonna cut it Buckwheat.
*Big giant goddamned KahBooooom!!!!* however that takes the head, neck and one arm with it and flings the rest 5 feet back? Now that's what I'm talking about!
Armor. As much as I love the romantic idea of suitting up and stepping out weapons in hand to face the horde, to lay waste to the shamblers and protect those I love the truth as it's a death sentence.
Imagine if you will, laying waste around you with your weapon of choice only to be snagged from behind and find yourself on the ground, arms and legs pinioned, no escape, no amount of pleading or bargaining.....you can't move and there are 100 hungry questing claws digging at you looking for chinks and holes. Eventually they are gonna get to you.
No, in my mind strike and evade, hide and ambush are the only possibilities for survival.