DENVER (KDVR) — The Boulder massacre has highlighted again the difference between assault rifles, assault weapons and non-assault weapons against the backdrop of new proposed weapons bans.

Gun control and mass shooting conversations are all about categories. Alleged shooter Ahmad Al Aliwi Alissa’s firearm meets some standards for “assault” but not for “rifle.”

Proponents of gun control legislation say every little bit helps, while opponents say weapons-specific regulations are largely arbitrary.

Assault vs. non-assault

The differences between assault weapons, assault rifles, non-assault rifles and carbines and pistols involve variations in capacity, purpose, looks, length and operations style.

Seven states and the District of Columbia currently have assault weapons bans, and the United States had an assault weapons ban enacted from 1994-2004.

Strictly speaking, an assault rifle is intended for military use and capable of firing in both semiautomatic and automatic modes. Since automatic firing is illegal in civilian weapons without special tax stamps, definitions become fuzzier in the civilian world for semiautomatic weapons.

As with mass shootings, there is no universally-accepted definition of “assault weapon.” However, there are broad strokes that separate what regulators deem an “assault” weapon or “assault” rifle.

Regulations focus on a range of functional and cosmetic features that broadly define it as “assault,” though this list is not exhaustive.

Typically, they have semiautomatic firing capability, meaning they can be fired as fast as the trigger can be pulled instead of reloaded by some manual operation after each shot.

Regulations often isolate detachable magazines rather than internal or fixed magazines. They also typically isolate magazines with 10-30 rounds of capacity, which is generally higher than the average rifle’s internal magazine’s capacity.

Regulations will also isolate pistol grips as an assault feature, as opposed to traditional rifle grips which are less vertical and supposedly less controllable when firing at a rapid rate. While other rifles may have a fixed shoulder stock, or butt, an assault rifle may have a collapsible stock that telescopes or folds.

An assault weapon may have a threaded barrel, which allows a flash or other attachment at the end of the weapon. It may have a barrel shroud, which is a vented metal tube that fits outside the weapon’s barrel to prevent accidental burns from the heat of the barrel during rapid fire.

Assault rifle vs. assault weapon

The Boulder shooting involves the difference between “assault rifles” and “assault weapons.”

From police and eyewitness reports, Ahmad Al Aliwi Alissa allegedly used a “long gun” in the King Soopers shooting. Police recovered another handgun and a rifle case from Alissa’s vehicle. On March 16, Alissa had purchased a Ruger AR-556 pistol.

The Ruger AR-556 comes in two models – a rifle and a pistol. The difference between the two is minimal. Both can be chambered for the same caliber round – the 5.56 NATO round – as well as other types of ammunition. Both have collapsible stocks, optional barrel shrouds and optional 30-round detachable magazines.

The pistol model, however, has a 9.5 inch barrel, while the rifle model has a 16.1 inch barrel.

The difference between a rifle and a short-barreled rifle, or carbine, is a matter of inches and dollars. Anything with a barrel beneath 16 inches in length is technically not a rifle but a short-barreled rifle, carbine or pistol.

U.S. citizens are allowed to own and operate shoulder-fired short-barreled rifles with barrels under 16 inches long as long as they are registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives. Owners must also pay the ATF a special tax stamp for the carbine.

Firearms manufacturers have variations of their products that comply with either federal or state restrictions on assault rifles. Some have fixed or low-capacity magazines, some have no threaded barrels or shrouds.

Some, like Alissa’s alleged weapon, have shorter barrels.

Weapons were developed to comply with the 1994 federal ban on assault rifles. Some of those have been used in high-profile mass shootings. One of the Columbine shooters used a Hi-Point carbine, among other weapons present.