1 Answers
A parts kit is a collection of weapon parts that, according to the Bureau of Alcohol, Tobacco, Firearms, and Explosives , "is designed to or may be readily be assembled, completed, converted, or restored to expel a projectile by the action of an explosive." As an example, the kit may not include a receiver or include an incomplete receiver. In most cases under U.S. law, the receiver must be serialized, and it requires a background check to purchase, among other considerations. This is different from other countries where pressure bearing parts such as bolts, barrels, and gas pistons are the regulated parts. A receiver can be purchased or manufactured to complete the firearm.
The National Firearms Act restricts the possession of automatic firearms, so most parts kits end up used with a semi-automatic receiver. In addition, under US gun law, a receiver that is legally a machine gun cannot legally become semi-automatic. There is no federal restriction on the purchase and import of machine gun parts kits , however.
Parts kits are available for many firearms including the AR-15 and AKM variants.