1. Trigger​
   Firing pin
2. Slide stock
   Hammer

Firing pins can help determine which gun was used in a crime because the pin leaves an imprint on the cartridge of the round when it is fired. However, firing pins can be swapped out, and the imprint wears down over time​, meaning this method is only partially reliable.

1. 1
   2
2. 3
   4

Though they only hold two rounds, over and under shotguns are some of the most reliable guns around. These shotguns have few moving parts, which make them easy to maintain and clean, resulting in a gun that will last a long time.

1. Breach
   Clip
2. Magazine
   Cylinder

The name revolver comes from the revolving cylinder that holds bullets in the gun. The invention of the revolver allowed handguns to hold more than two bullets for the first time.

1. .17 HMR
   .223
2. 10 mm
   .22 LR

The FBI started using 10mm rounds after the 1986 shootout in Miami where two FBI agents were killed. However, the rounds were hard to control because of their recoil power and were eventually abandoned.

1. Powder
   Ammo
2. Oil
   Baking soda

The Chinese discovered gunpowder and its effectiveness as a chemical explosive around the 8th century. However, the original use of the powder was for fireworks.

1. Smith & Wesson
   GLOCK
2. Ruger
   Taurus

The GLOCK brand was founded in Austria by Gaston Glock. The company has one production facility in the United States which is located in Smyrna, Georgia.

1. GLOCK
   Heckler & Koch
2. Colt
   Ruger

Samuel Colt was an inventor who patented the revolver in 1836 after developing the idea while at sea. His company learned how to construct​ the gun at a rapid rate, and within 25 years of the company's existence, hundreds of thousands of revolvers had been built.

1. Rebuild
   Field strip
2. Checkup
   Maintenance​

Military members have been trained to field strip a weapon as quickly and efficiently as possible. They are even taught to perform the practice in the dark in case a scenario arises where they need to repair their gun without seeing it.

1. Gold
   Loaded
2. A child
   Your last

A gun should never be taken for granted, even if you're confident it's not loaded. When a gun is being passed around, the barrel should always be aimed away from the other person.

1. Tritium
   Helium
2. Copper
   Argon

In gas form, tritium is odorless and colorless. However, the element is more likely to be found in its liquid form, which has a chemical formula of T2O.

1. Clip
   Barrel
2. Magazine
   Stock

Many states have high-capacity magazine bans which means magazines can only hold a certain number of rounds. For example, California defines high-capacity as any magazine that holds over 10 rounds.

1. Remington 870
   Mossberg 500
2. Browning A-Bolt
   Beretta A-400

The Browning A-Bolt is a popular gun used for hunting, especially in the United States. The gun is hailed for its accuracy, since it has an effective firing range of 1,000 m.

1. Thermal
   Red dot
2. Holographic
   Reflex

Thermal optics are particularly great in areas with heavy amounts of snow. The extreme cold creates a disparity between the snow and the heat source a gun operator is seeking out.

1. 4
   5
2. 6
   7

The 1911 handgun gets its name from the year 1911 when it was adopted by the United States Army. The original design for the handgun came from John Browning and was named the Model 1911.

1. A belt
   A holster
2. A strap
   An insert

Holsters are critically important when it comes to gun safety, particularly for those who carry. The most important thing a holster should do is cover the trigger. Otherwise, the gun is left vulnerable and can easily fire.

1. Inside the weight band
   Inside weighted bullet
2. In the waistband​
   Improved weighted bullet

Holsters should easily fit guns without any functional issues. An owner should be able to draw and reholster a gun without the gun catching or snagging on the holster.

1. AR-15
   AK-47
2. Howa 1500
   SCAR 16-S

Many gun critics often confuse the "AR" in AR-15 as standing for "assault rifle." However, it actually stands for "Armalite rifle," as assault rifles are banned from civilian use.

1. The hammer
   The trigger
2. The muzzle
   The stock

The weight of the trigger pull can be altered on firearms to make the trigger easier or more difficult to pull, causing the gun to fire. However, a lighter trigger pull can often result in legal ramifications if the gun is used in self-defense​ as negligence can be cited more easily.

1. The pistol grip
   The foregrip
2. The receiver
   The stock

Bump stocks have become heavily criticized in recent years because they allow rifles to be fired at a quicker rate. A bump stock works by using the energy from the gun sliding back and forth to increase the rate of fire.

1. Bayonet
   Katana
2. Sabre
   Spear

European militaries started using bayonets as early as the 17th century. Originally, bayonets fit on the end of a muzzle in a way that wouldn't allow the gun to fire.

1. The safety
   The muzzle
2. The breech
   The hammer

The most common type of safety traditionally used on guns is a lever safety which requires manual operation. It must be flipped off in order for the gun to fire.

1. When it's pulled from the holster
   When it's in the holster
2. As you pull it from the holster
   When you are ready to fire

The final step in firing a weapon is putting your finger on the trigger. As soon as your finger touches the trigger, you should be on your target and ready to fire, not pointed off somewhere else.

1. Hidden carry
   Concealed carry
2. Legal carry
   Protected carry

Most states require some type of permit for gun owners to conceal carry their weapon. However, some states, like Mississippi and Kansas, do not require a permit for guns to be concealed.

1. Press safety
   Hold safety
2. Grip safety
   Push safety

Grip safeties are useful because they require an operator to hold the gun properly before it will fire. If the gun is not held in the proper firing position, it will not go off.

1. Full metal jacket
   Slug
2. Birdshot
   Pellets

Shotgun slugs are typically made of lead or copper. They are very beneficial in hunting larger game as they have a stronger force and impact when they hit the target.

1. Pump-action
   Single-action
2. Sawed-off
   Break-action

The barrel of a shotgun is occasionally shortened in what becomes known as a sawed-off shotgun. Without​ the extended barrel, the gun becomes easier to carry and maneuver.

1. Pump-action
   Bolt-action
2. Lever-action
   Single-action

Pump-action shotguns aren't known for their accuracy, which is why they are used in close quarters instead of at long distances. Often, they make great home defense weapons since you are more likely to hit your target when they are a few feet away with a shotgun.

1. 1808
   1864
2. 1887
   1910

John Browning was one of the earliest American firearm designers. He was awarded over 100 firearm patents throughout his life as he helped usher in the era of automatic and semi-automatic weapons.

1. Diameter
   Caliber
2. Gauge
   Meter

Often confused, a smaller shotgun gauge means the shotgun bore is actually larger. The 12 gauge shotgun is the most popular shotgun in the United States, making up nearly 50 percent of the sales.

1. Marking
   Rifling
2. Soldering
   Carving

Rifles are designed for long-range targets, which is particularly useful in deer hunting. By rifling the barrel, bullets can stay on course for a longer duration.

1. Projectile​
   Primer
2. Case
   Propellant

One of the most popular and powerful handguns is the Smith & Wesson .44 Magnum, which was used by Clint Eastwood in the film "Dirty Harry." The gun carries a projectile with a diameter of .429 inches.

1. Hollow point
   Soft point
2. Special
   Full metal jacket

Full metal jackets are popular practice round bullets that you will find gun owners firing at the range. Their popularity on the range comes from the cheaper price they carry.

1. Hollow point
   Soft point
2. Special
   Wad cutter

Since hollow point bullets expand when they hit a target, they have much more stopping power than a full metal jacket. With that stopping power, these bullets are more useful in home defense.

1. Easy point
   Soft point
2. Half metal jacket
   Light metal jacket

Soft point bullets have much more stopping power than a full metal jacket which can be beneficial when hunting larger animals. However, they don't quite have the same stopping power as a hollow point bullet, which is why they aren't as popular.

1. Turns off the safety
   Loads the bullet
2. Aims itself
   Cocks

Double-action pistols have a much stronger trigger pull than single-action pistols. The stronger pull allows the hammer to cock before it drops back and fires the bullet.