This is a 2.0 version of the guide since my old account got banned. I wanted to include more pictures and some videos.
First off Future Weapons and Ultimate Warrior are shows meant for entertainment purposes. I've heard they can be total idiots when it comes to getting their facts right. All I have to say is don't take them too seriously. Take it all with a grain of salt.
The Four Rules of safety are often the cornerstone of weapons safety. The order may vary, but essentially these are the rules. The majority of accidental injuries/deaths from guns could have been avoided if these rules were followed.
1. A gun is always loaded.
2. Never point a gun at anything you aren't willing to destroy
3. Always keep your finger off the trigger until you are ready to fire
4. Always be aware of your target and what lies beyond.
The first rule pretty much covers everything, but the other rules are still there to clarify for those who don't figure out the safety tips. Some times the rule is stated as "treat" the gun as if it were loaded. I prefer to just say the gun is always loaded. You need the frame of mind that the gun is loaded. If you fool around and play with guns like it's a toy that's when people get shot. The second rule is pretty self explanatory. Some people think the safety will save them. I wouldn't trust the safety to work. If you fool around with the gun because the safety is on some time the safety might not be on or it could be broken and someone could be hurt. If you're screwing around you might accidentally shoot someone. The third rule is to help prevent you firing when you are not ready. If you keep the finger on the trigger while you are still aiming you might fire off a shot prematurely. If you're hunting you might wound the target without killing it. The 4th rule is vitally important. If you're hunting and you see a bush shaking you better be 100% positive what you are shooting at. If you accidentally shoot a hunter instead no matter how sorry you are or how much you pray God won't bring them back. There is also a thing known as over penetration where your bullet goes in one side of the target and out the other. Anything on the other side of your target could be hit so be careful. There are various other safety procedures, but the four rules are the big ones.
Additional Safety should be exercised with guns. Further on I have a section about how to store guns. When you transport a weapon it's a good idea to make sure the weapon is unloaded. When you handle a weapon but not actually using it you should make sure it's not loaded. When you're shooting and you think your gun is empty you should first remove the magazine then open the chamber and make sure it's empty before you set it down. You should never leave a gun unattended if children are around. Really a lot of gun safety is common sense. If you lack common sense you shouldn't really own a gun.
Clips and Magazines are ammo holding items used for loading weapons. Usually when someone talks about a clip they are really talking about a magazine. Some people make a big difference between the two. I think if you know what is meant that is good enough. Still I might as well cover it. A magazine is what loads the ammunition into the gun itself. It is the ammo belt for a machine gun, a cylinder for a revolver, or the banana shaped box in an AK47 are all examples of magazines. A clip is used to load a magazine. Many older weapons had a magazine permanently attached to the gun itself. A "stripper clip" was used to slide several rounds into the magazine at once rather than having to put in 1 round at a time. If you are in doubt refer to the picture below.

Bullets are the projectiles fired from guns. Yes I know any idiot can figure that out. The thing is the bullet is sometimes mistaken as being the entire ammunition unit. A single ammunition unit is often called a round or cartridge. A cartridge consists of a projectile (the bullet), propellant (the gunpowder), the primer (the thing that sets off the gunpowder) and the casing (the metal tube that holds everything together. The diagram below shows everything.

Caliber refers to the diameter of the ammo. It is sometimes measured in imperial and other times in metric. Imperial is in hundredths of an inch, or in some cases even thousandths such as .45 and .223. Metric is in millimeters such as 9mm and 7.62mm. If you're just talking about guns that's all you need to know, but if you actually want to own a gun you will want to learn the specifics. For example there is .22 short, .22 long, and .22 magnum. All three of them are .22, but they aren't necessarily the same. A .22 short won't hold a '22 long or magnum. The same with 9mm. There is 9mm parabellum is 9x19mm while 9mm Makarov is 9x18mm. If you were to try and use a Parabellum round in a gun that takes a Makarov round you would find the round is too long. One millimeter doesn't seem like a big deal, but it can make a big difference.
Shotgun calibers are measured differently. There is the .410 which is 41/100 of an inch like I discussed earlier. Other than that shotguns are measured in gauge. The smaller the number the larger the diameter. This is because gauge is measured in fractions of a pound of lead. 20 gauge for example is the size of a sphere of lead that weighs 1/20 of a pound. A 12 gauge is the size of a sphere of lead 1/12 of a pound. That's how the smaller number makes a larger caliber.
Buying Advice So maybe you want to buy a gun but you have no idea what you should get. Well here are a few pointers to keep in mind.
1. Choose a gun that fits your need. If you want to hunt deer and elk a good rifle is what you will want. If you want to hunt birds a shotgun is what you want. For home defense a good handgun might be worth choosing. If you just want an inexpensive gun where you can do a lot of target shooting just about any .22lr gun will do.
2. Ammo availability is a very important thing to consider if you want to buy a gun. You will probably want something that is easy to get ammo for. The FN P90 looks nice and handles nice in video games, but the 5.7mm ammo is pretty rare in the U.S. so even if you could get one the ammunition will be hard to get and expensive. If you plan to do a lot of target practice without the intent of using the gun for self defense a .22 is good to get. The ammo is the cheapest available so you get more for your money.
3. Choose ammunition that suits your need. If you're hunting birds you don't want to use buckshot. If you're choosing home defense you will probably want at least a 9mm. I will go into detail with caliber later.
4. Choose a weapon that suits you. It's good to have friends with weapon experience. It's a good idea to try various calibers before buying. Guns and ammo can be expensive so it's good to get a feel for what works best for you rather than just buying something that feels too awkward.
Storing Firearms is somewhat controversial. It's widely accepted you need to secure your guns, but to what degree is the issue. Some people think you need to lock your guns in one safe, your ammo in another safe, and have each safe on opposite sides of the house. This makes your guns most inconvenient for an intruder to use against you, but is also inconvenient for you to use against intruders. What can be agreed on is that weapons should be locked up especially when you are not directly using them. If you leave it in an unlocked drawer a thief can find it when you're not home. Even worse if you have If you own a gun it's your call how you secure it. It's your responsibility to keep them properly secured and your fault if something happens if you fail to.
Automatic Weapons are a big hot button for the media. An automatic weapon is a weapon that automatically reloads itself after it fires. There are Semi Automatic and Fully Automatic weapons. Semi automatic weapons are a weapon that will fire once and then reload when you squeeze the trigger. If you squeeze the trigger and hold it down it still only shoots one time. If you keep pulling the trigger it will keep firing until you run out of ammo. Fully automatic weapons are weapons that can keep firing and reloading. If you hold down the trigger it will fire then reload then fire and reload again. It will keep firing and reloading until you release the trigger or you run out of ammo. Fully automatic weapons are heavily regulated so to legally purchase one is difficult and very expensive. This video is a good demonstration of the difference between the two.
Assault Weapons are a difficult classification of weapons. Different sources have different definitions. The media has a tendency to use this term to scare people. The assault weapon ban of 1994 classified an assault rifle as a semi automatic rifle able to accept detachable magazines with two or more of the following features.
1. A folding or telescoping stock. These are stocks can reduce in size making a weapon more compact.
2. A pistol grip. These are grips that extend below the stock of the rifle giving you a better grip. A firm grip helps you hold your rifle better making it more accurate.
3. A bayonet mount. This is a mounting point on a long gun where a large knife can be mounted so your rifle can be used as a spear for stabbing. Flashlights can also be mounted here.
4. A flash suppressor or threaded barrel to accomodate one. When you fire a gun some flame spits out the front. A flash suppressor disperses this flame making it harder to see.
5. A muzzle device which enables the launching of rifle grenades. That's just a fancy way of saying a grenade launcher.
Assault weapons ban also extends its definition to pistols and shotguns. Long story short if it makes it easier to kill people it was on the list of banned features. Features like high capacity magazines can be understandable, but some features are just stupid like the unloaded weight of a pistol has to be less than 50 oz or a pistol grip on shotguns.
In a nutshell assault weapons are just guns that "look scary".
Silencers are a common name used for a sound suppressor. Sound suppressor is the official term used. They are popular in video games and movies. When you use them in video games and in movies it should be noticed that you almost always hear the guns going off anyway. It is much quieter, but it still makes noise. For some reason there is a misconception that they make the gun completely silent. Such is not the case. A sound suppressor is a chamber on the end of the gun for expanding gasses to expand into. It works exactly the same as a car muffler.
This video is a good comparison between the two. It should be noted that while the suppressed gun is still much quieter than the non suppressed gun it is still louder than what is shown in the video. These guns are .45 which are pretty loud in person, much louder than indicated by the video.
Sniper Rifles and Hunting Rifles are similar weapons. Hunting rifles are sometimes identified as sniper rifles. The two are more or less the same. If you watched the video in the Automatic section he explained the difference a little. The main difference is how the name sounds. A hunting rifle to the average joe is an average weapon while a sniper rifle is a high powered weapon that can easily kill in one shot. Sniping tactics were based on hunting tactics. A person does their best to remain undetected while they search for the animal they want to kill. When they find the animal they carefully place an accurate shot to a place on the animal to kill them in one hit. Actually the term "Sniper" refers to a marksman who was accurate enough to shoot a snipe. The same is the principal behind sniping. Since hunting relies on accuracy the weapon is designed to shoot accurately. An actual military sniper rifle isn't as easy to get ahold of but a good hunting rifle can be used for sniping all the same. I don't say this to scare you. The truth is with all the hunting rifles out there if they were really a threat there would be a lot more snipings then there have been.
Less than Lethal weapons are weapons designed to stop a target without killing them. These are tasers, stun guns, sticky shockers, beanbag shotgun shells, rubber bullets, and many more weapons. They are sometimes called non lethal weapons, but that is a misleading title. If improperly used it can still kill a target. Still they are designed to take down a target without killing it.
In Conclusion I hope you have learned something from this guide. When I mentioned to take shows like Future Weapons and Weaponology with a grain of salt the same applies to this guide. This guide is not absolute fact written in stone. I mean for this guide to be taken seriously though.