If you try to buy any firearm in the U.S.A., you will be subject to a criminal background check via the ATF. However there are weapons or guns that do not fall into the “firearms” category because of how they propel a projectile. If you use an explosive to propel a projectile then the device is a firearm. If you use compressed gas to propel a projectile, it is classified as an air gun or pellet gun. Air guns and pellet guns do not require any kind of background check and anyone 18 years of age or older can purchase an air gun. Air guns are indeed weapons and can kill a human. See this article on best air guns for self defense.
So how powerful are air guns? Velocities of 1,250 fps are common in most air rifles. Some of the larger calibers (.357, .458, .62) shoot larger pellets or cast bullets at 800 fps. The larger pellets or cast bullets at lower velocities can still kill. .177 and .22 caliber air rifles can easily kill small game and humans. Some people are looking at bb guns for self defense in locations that prohibit firearms. A high powered air gun is much better than a stick for self defense.
There are several companies (Umarex) making full auto bb guns. The velocities are lower though, around 450 fps but could still do some serious damage at close range. If the muzzle velocity were increased to 1,000 fps, these would be very lethal.
Another interesting aspect of air guns is the noise level. They are pretty quiet compared to a firearm. Some are very quiet because they employ a suppressor on the barrel. Very little public disturbance is caused by the discharge of an air rifle, it almost goes unnoticed. The sound of a firearm discharging sends people into a panic. 911 being dialed immediately.
The air gun has many appealing aspects. To the hunter, it is a real gem…no hearing protection needed. If you are a hunter, you know how much of a pain hearing protection is and muzzle blast. Air gun hunters need no hearing protection at all. Even more appealing is the fact that an air gun discharge or firing will not scare game away like a firearm does. This gives you more opportunities. Ammunition for an air gun is much lighter than firearm ammunition and cheaper too.
Think about some more advanced air guns for the military. Soldiers could sneak up and take out targets without anyone knowing. Silence is golden in battle. Air guns also leave not evidence behind…no spent casings and no muzzle flash. The possibilities are exciting. Read more about advanced technology air guns at Pellet Guns 1.