Today, nearly every major firearm manufacturer produces its own generic AR-15–style rifle. As Colt continues to own and use the AR-15 trademark for its line of AR-15 variants, other manufacturers must use their own model numbers and names to market their AR-15–style rifles for commercial sale.

True gun. According to Tonio Andrade, a historian of gunpowder technology, a "true gun" is defined as a firearm which shoots a bullet that fits the barrel as opposed to one which does not, such as the shrapnel shooting fire lance.

FBI SWAT is known to use the M4 carbine, Heckler & Koch MP5/10, Remington 870, Remington 700, various Glock models (17 Gen4, 19M, 20), SIG Sauer P226, and Springfield Armory 1911 Professional Custom.

Black powder percussion guns are the closest you'll get to a regular gun on this list. You'll still find gun powder, a projectile, and a miniature contained explosion. And, of course, you need ears, eyes, and a safe place to shoot. Black powder guns are a very broad category with rifles, shotguns, and pistols.