I spent two months shy of 4 years in the army from 1965 to 1969 first as enlisted and then as an officer. I had one partial tour in Nam where I was wounded and sent home to recover after 4 months in combat. I was qualified with most infantry weapons and used a CAR-15 (Colt Automatic Rifle-15) in Vietnam which was a short barrel version of the M16 riffle. The more modern version of that rifle line is the M4 and a civilian look alike is commonly referred to as the AR-15 Assault rifle. The civilian AR-15 cannot fire full auto even with a “bump stock” add on, it still requires a separate trigger pull for each round fired. In Vietnam on patrol I never fired my CAR-15 on full auto; it’s a waste of ammo in most cases. In the jungle often with no communications you didn’t waste your ammo.

The following is a quick summary of the various kinds of guns or weapons made as simple as possible. Manufacturers and others give brand names and descriptions to models they make and there are all kind of fancy add-on’s most, if not all, are meaningless to the actual function of the weapon; which is feed a round into the chamber and fire it with a trigger pull. Not considered here, are the various kinds of bullets but it must be kept in mind that the bullets are designed to kill, there is no such thing as a safe bullet.

But first I have a test for you, below are the images of two weapons, what is the main functional difference between them, assume they are civilian weapons?  At the end of this post I will give you the answer.

Forgetting muzzle loaders there are really only two kinds of guns (including; hand guns, rifles, machine guns and shot guns) the first and most common kind is where one trigger pull fires one round. The other kind is when a trigger is pulled, and held, the weapon will continue to fire until either the supply of bullets is gone or the trigger is released. Some of the different common names are: machine gun, revolver, semi-automatic, rifle, carbine, long riffle, shot gun and derringer that refer to the means of feeding a bullet into the weapon and the length of the barrel.

Bullets can be placed in one at a time as in a derringer, or 6 in a cylinder that can be placed in the revolver, or a small number from 3 to 8 or more in a feed tube under the barrel of a lever action rifle, or a pump action shot gun, or in a clip of 5 bullets that can be pushed into the opening under the bolt as in the old M-1 Garand rifle of WW II, or in a magazine that holds 5 to 30 bullets or more like a AR-15 or M4 or AK-47, or a belt of bullets held together by small metal clip of 100 or more bullets as in a M-60 machine gun.

The next consideration is how the bullets get into the position to be fired; which can be a rotating cylinder, a hand operated bolt, a pump action, a lever action, a mechanism related to the energy contained in the detonated charge in the bullet that will directly or indirectly cause the bolt to move back into a position where the next bullet can be feed in (commonly referred to as a semi-automatic).

For all practical purposes, from a functional point of view, there are only 4 kinds of guns or weapons:

Civilian Weapons (some also used by the military):

1 Semi-automatic single pull and release trigger with a short barrel

2 Semi-automatic single pull and release trigger with a long barrel

Military Weapons: 

3 Full-automatic and single pull and hold trigger with a short barrel

4 Full-automatic and single pull and hold trigger with a long barrel

The problem that the people that don’t like the 2nd Amendment, and want to ban guns, have is that there is no way to actually ban “assault” rifles as it does not appear as a type of weapon: it’s a look, not a kind of weapon. It would be like trying banning Kleenex tissue. The closest actual type would be a scout rifle or a carbine which are short barreled rifles. Legislation that these people try to write, as to what constitutes an assault rifle, end up having a great many pages of descriptions as they try and describe something that does not actually exist.

The answer to the quiz is the biggest functional difference between those two weapons is the length of the barrel.