I've been interested in weapons of all kinds since I was in about junior high and I worked at Cabela's for 9 years, five of which I spent selling firearms. I also own and use firearms. In addition, most of what I write includes weapons of some kind.
I tried to keep this presentation as informative and as politics free as possible. I know how much of a hot-button issue firearms are and didn't want to get into it during the class.
Gunpowder was invented in the early 9th century in China and was used for medicinal purposes. The first record of it being used in warfare was in 904. Gunpowder finally made it to the rest of Asia and into Europe in the 1300's on the Great Silk Road. The first hand-held firearms were hand-gonnes (top picture) which were essentially metal tubes on sticks that had a hole at the rear to ignite the gunpowder using a candle or burning stick. Matchlocks were invented in the late 1600's which had a lit wick on a mechnisim that would drop onto the powder pan when the trigger was pulled, igniting the powder and causing the bullet to fire.
Then came the wheellock and flintlock (bottom picture) guns that used flint against steel to create sparks that ignited the gunpowder. Most of these early firearms were smooth-bore which means the barrels were just simple metal tubes without rifling. Rifling is a spiral groove cut into the inside of the barrel that causes the bullet to spin, increasing the accuracy of the bullet.
This period also had an early form of a shotgun called a blunderbuss (had a flared muzzle that kind of looks like a trumpet). These were loaded with lead shot but could fire pretty much anything you could load into it.
The ammo that was used were simple lead balls or lead shot which consisted of lots of smaller lead balls.
Repeating action guns came about in the mid 1800's and were made possible by cartridge ammunition (two types, rimfire and centerfire).
Lever action and revolvers were the first forms of repeating action guns with semi-automatic not far behind. The first automatic weapons were Gatling guns using during the Civil War.
Black powder rifles are still used today but they are fairly different than the original flintlocks. They use a primer to ignite the powder in the barrel and come as both muzzle loaders (load the powder and bullets from the muzzle end, tamping everything down the barrel with a ramrod) and breach loaders (the barrel breaks open and the bullet and powder are loaded from the breach end).
Next-Gen and smart weapons: companies are developing firearms that read the user's fingerprints and will only fire for the person whose prints it recognizes. There are also firearms in the works for police officers that have a chip in them that read a corresponding chip in the officer's badge so it will only fire from a certain angle. This is to prevent officers from being injured or killed with their own weapons.
Smart bullets are getting more into sci-fi territory. There are companies that are working on bullets that can change their trajectory mid-flight making it easier to account for wind and moving targets. Information gathering bullets are also being developed, making essentially "spy bullets" that can report back intel.
Clips (left picture) are a piece of metal that clamps ammo in place. They're usually used for WWI/WWII era military rifles. They can be used by inserting the whole thing into the chamber of the rifle and when all of the rounds are fired, the clip pops out the top or you would just line the clip up with the chamber, push the rounds into the gun, and pocket the clip.
Magazines are fully contained and use a spring under a plate to deliver round into the chamber, usually from the bottom of the chamber.
According to the ATF, long guns are firearms meant to be fired from the shoulder, legally having a barrel that is 18.5 inches or longer.Unless you have a special license, it is illegal for people to have long guns with barrels that are shorter than 18.5 inches long.
There are two types of long guns: rifles (right three pictures), these shoot bullets and have a rifled barrel; and shotguns (left picture) that have a smooth bore barrel and shoot lead shot in a scatter pattern.
The ammo is not a hard rule. They do make shotshells for rifles, usually in rimfire calibers, they look like bullets full of sprinkles. They're primarily used for rattlesnakes and pigeons. You can also get slugs for shotguns, it's a good idea to get a rifled barrel for your shotgun if you plan on using slugs.
Optics vs iron sights- optics (scopes red dots) are used primarily on rifles that don't have iron sights like the top rifle on the right. The bottom two rifles both have iron sights which consist of a single post at the end of the barrel that you line up between the U-shaped sights towards the rear of the gun. Shotguns usually have a single bead sight at the end of the barrel, sometimes they have a second sight towards the rear of the gun.
"Sniper rifle" is not really a term used in the industry. A sniper is a person who is a well-trained shooter. Any rifle they use is a "sniper rifle." There is no gun that you can point at and say "that's a sniper rifle." In fact, the top rifle on the right is a Remington 700 and is one of the most popular guns snipers use. They do add special barrels, triggers, and amazing optics to increase their accuracy.
"Assault rifle" is another term not used in the industry. It's usually applied to AR-15 style rifles. The AR actually stands for Armalite Rifle, Armalite being the company that developed the rifle. AR-15 is the specific model of the Armalite version but other companies make similar rifles but have different model names. Use terms like AR-style, modern sporting rifles (MSRs), or even black guns (comes from the fact that they're usually black, super advanced, I know).
There are two types: pistols, the ammo is delivered by a magazine that is fitted into the grip (top two pictures; and revolvers, where the ammo is delivered from a revolving cylinder (bottom two pictures).
Glock and pistol are not synonymous. Glock is a handgun manufacturer in Austria who make one of the most popular handguns in the world.
Single action: you have to pull the hammer back to fire the gun (examples: 1911 first picture, replica 1841 revolver fourth picture)
Double action: revolver with no external hammer, usually on conceal carry guns like the Ruger J-frame style (third picture) so there's no hammer to get caught on clothing, purses, or holsters reducing the chance of misfiring
Single-double: revolvers that have hammers but can be fired with or without pulling the hammer back, without pulling the hammer back results in a long trigger pull, pulling the hammer back shortens the trigger pull.
Suppressors do. They do reduce the noise a firearm makes but it will still be loud, like a door slamming. You have to have a Class 3 license to purchase one.
A ton of movies and shows have a red dot showing up on somebody's chest or head, indicating that they are in a sniper's sights and are about to be killed. Snipers aren't going to use a laser sight. Snipers have two primary objectives: 1) kill their target; 2) don't give away their location. Lasers warn the target, giving them time to get out of the way and give away the sniper's location. You also have to sight lasers in like you do scopes. If you sight them in for 100 yards and try to shoot somebody at 50 yards by putting the laser on their chest, you'll shoot over their head.
Semi-Automatic: means you pull the trigger, a round is fired, the shell is ejected, and the next round is loaded into the chamber, then everything stops.
Automatic: pull the trigger, a round is fired, the shell is ejected, and the next round is loaded into the chamber, cycle continues until you release the trigger. Made for short bursts, too much use will burn up the barrel.
Machine gun: automatic weapon that is made for near-continuous use.
Automatic and machine guns are terrible for accuracy. There is a lot of lift when they're being fired and unless the user has great control over it, it'll be hard to actually hit something. They're made for suppressive fire or distracting the enemy. Their motto is accuracy through volume.
List of approximate capacities for different kinds of firearms. See the manufacturer's websites for accurate capacity for the gun you are using. There are plenty of after-market accessories that will increase capacities, ex: 30 round mag for a Glock 17 or a 50 round drum mag for a Ruger 10/22 rifle.
History: make sure you are using firearms that are correct to the time period, don't want to be using a lever action rifle during the Revolutionary War.
Geography: some firearms are not accessible or allowed in parts of the world. Ex.: there is a ban on surplus military rifles (like Mosin Nagants or SKSs) being imported into the US so you can't find a new one in a store anymore.
Helps with realism. I read a book once about a French resistance group during WWII and I'm pretty sure the author didn't know any other guns that were used in WWII besides an Uzi (second picture) because every single person in the group used an Uzi. Resistance fighters would have pilfered their firearms anywhere they could find them. They were also supplied by the Allies so they would have used any combination of French, German, American, British, etc firearms
Glocks are one of the most popular handgun in the world because of its durability. It is used a lot by law enforcement agencies but it is not the only firearms used for service weapons. Many police departments get surplus military handguns and up until about 3 years ago that was the Beretta M9. The US military has since moved on to a Sig Sauer handgun that is a bit more versatile. Glocks are one of the only handguns that I have ever heard of that can be fired underwater but you'll only get one shot off before it's useless.
If you want a character to continuously pull the trigger and get that click-click-click effect that you see in a lot of movies once all of the bullets are fired, give them a revolver, not a pistol. A pistol slide will lock back (bottom picture) and while the trigger keeps moving, nothing else happens.
Range of accuracy: with the right caliber and the right shooter, a bullet can go a mile but it's a pretty tough feat. Meanwhile, a gun like a derringer (top picture) is accurate up to about 8 feet, it's meant to be shot across a poker table, you'll struggle to hit your target from across the street, although they do make them in higher calibers and longer barrels now that have increased their range of accuracy.
With sci-fi weapons, it's really author's choice for how they work but having a basic understanding of how firearms operate will help make them more realistic.
Manufacturer websites give you specifics about their firearms.
Brownells sells afermarket accessories like magazines, optics, sights, grips, barrels, etc.
State law enforcement agencies will give you state firearm regulations. You used to be able to find these on the ATFs website but when gun regulations started changing very quickly, it's tough for them to keep up.
Other countries will have their own versions of the ATF where you can find their firearm regulations.
Local gun clubs/gun shops are a wealth of gun knowledge. It sounds like a stereotype but old gun guys love talking about guns. I used to work with a handful of them and had plenty of customers who fit in that category. They'll spend hours talking guns with you if you let them.
IMFDb lists firearms used in different movies, it's really great for sci-fi movies where they take real firearms and modify them to make them look more futuristic.
