First, some rules.
1. This is a serious topic. This discussion is about matters of life and death for you and those around you. Stay focused.
2. If you're going to contribute, you better have had actual field experience with whatever you're bringing to the table. I don't want to hear about how badass a gun is because you use it when you play Call of Duty or because you once fired your buddy's AR.
3. Keep it legal. DO NOT talk about converting any semi-automatic in to a full-auto. This is illegal no matter where you live.
4. Feel free to ask questions. The only stupid question is the one not asked.
Having said that......
You're selection of a firearm may be a matter of life and death. Your very existence may very well depend on the firearm you choose. Hopefully this discussion will be a guide to help you make the right choice.
The first thing I would look at is a military-grade semi-automatic rifle. Remember, when dealing with the zombie threat, you're trying to make head shots. Engagements will generally occur within 100 yards. At this range, most military rifles made in the last half century will do. Bolt-action require the user to manually eject and reload after each shot. This problem is eliminated with semi-autos.
Second thing to consider is time it takes to reload and the amount of ammunition that can be practically carried. Military rifles generally have a detachable magazine that can be changed in a matter of seconds with practice and can usually between 20 and 30 rounds. A person in moderately good shape can comfortably carry 10 of these magazines giving them immediate access to 200-300 rounds.
Because of these two reasons, I am not including shotguns. Shotguns are very limited in their range and ammunition capacity. Ever #00 buckshot fired at 100 yards does next to nothing to the target because the spread is so wide. Also, most shotguns use a fixed tube magazine under the barrel, limiting their capacity to 8 or 9 rounds and have to be reloaded with one shell at a time. Models like the Saiga-12 shotguns with their detachable are limited to a dozen rounds or so and with a magazine that weighs more than and AR magazine loaded with 30 rounds.
Civilian semi-automatic rifles made to military specifications are built to take the abuse of the battlefield. There is no such thing as a perfect weapon. They are machines, pure and simple and will malfunction at the more inappropriate time. Training and familiarity with these and any weapon is critical in their application. Malfunction drills should be practiced over and over again until reacting to a malfunction comes as naturally to the shooter as sighting in and squeezing the trigger.
Handguns should never be considered for your primary firearm; there's a reason they're called sidearms. By nature, they are underpowered and should only be used because your rifle cannot be used for one reason or the other. Their range is limited due to the power of the ammunition.
I'm not going to go into detail about makes and models due to the fact that they should be considered secondary firearms. The two biggest factors to consider is the reliability of the weapon and the caliber.
Stick to common calibers. If you're sidearm is chambered in 9mm, .40 S&W, or .45 ACP for autos or .38 or .357 mag for revolvers, you'll be set. These are the most common calibers in America. All of those listed have been staples in the law enforcement community and/or the military at one point or another. It is plentiful and easy to find.
As far as makes go, Glocks are in my opinion the easiest sidearm for anyone to learn how to use. They are reliable and damn near indestructible. Other reputable manufactures include, but are not limited to Springfield, Colt, Smith & Wesson, Ruger, Taurus, Beretta, and Browning.
Avoid Hi-Points like the plague!
Shooting is an art. After decades of movies and TV, many believe that all a person has to do is point a gun in the general direction of the target and the bullet will magically hit what you want it to. Nothing could be farther from the truth. The importance of practice cannot be stressed enough.
This does not mean going to the range every day and shooting a bunch of ammo. Dry practice in your home for 10-15 is all you need.
Start by making sure your ammo is in another room and that your weapon is clear.
Place a target on a wall, shelf or table.
For rifles, practice your presentation from the alert (muzzle down) to the Ready (sighted in on target)
In the case of sidearms, practice presentation from the holster to the ready.
Don't worry about squeezing the trigger. Instead, concentrate on lining up the sights and focusing on the front sight of the weapon.
Repeat this process over and over until it becomes second-nature. Remember, and amateur practices until he gets it right, a professional practices until he can't get it wrong.
There's no such thing as having too many. If you're long and/or short uses them, get more. Most can be had for between $10-20. Try to stick to factory mags or else ones made by a reputable third party manufacturer of high quality.
Unless you're shooting beyond a couple hundred yards, you don't need a 10-power scope. Simple red dots will suffice for the type of shooting we're talking about here and allow for faster target acquisition than traditional iron sights.
For sidearms, I would recommend investing in a set of Trijicon sights for target acquisition in low-light.
That's all I've got for now. Feel free to ask any questions.
Yeah but that was back in the 1800's. Guns and ammunition have certainly changed from from that time and what might have worked back then might not work now.