"Come on in the year 3000 we are still going to be trying to follow documents from the 1700’s…it’s absurd"

What do those doccuments say that you dissagree with, exactly?

I have an assignment to everyone here who suggested that a 12 ga shotgun would be the best weapon period: Go to the store and find a box of 100 12 ga shotshells and just pick it up. Weighs a bit doesn't it? 100 rounds is a few hours of skeet shooting, you'll need to carry a lot more if you want to fight zombies. Second, most models of shotguns have a tube magazine where you must load it 1 shell at a time, where most magazines hold 4 and depending on the model up to 8 in the tube. I don't know about you but I don't want to have to insert each round one-by-one every 5 shots when I have a swarm of zombies after me.

So keep the shotgun at home for hunting, which you'll be doing a lot of in a post apocalyptic world.

Here are some things you might actually want:

.38/357 lever action rifle, +1 if you can get a matching revolver as a backup. If you jam a revolver you've messed it up anyway.

a good .22 caliber magnum rifle

SKS: durable, ammo is pretty easy to get, and with stripper clips you can reload them pretty fast.

Old surplus bolt action rifles: Mosin-Nagant, Enfield, K98, and 1903 Springfield are all very reliable and accurate for medium to long range shooting and ammo is readily available for all of them. Although I mentioned Bolt-action the M1 Garand is also a great gun.

P.S. chainsaws are in infection hazard as they will spray zombie goo all over you, do you really want that?