An assembly package designed for constructing a specific type of firearm, it typically comprises the essential components required to create a functional pistol, excluding the frame or receiver in some instances due to regulatory considerations. As an example, such a package may include the slide, barrel, internal springs, and small parts necessary to complete the upper portion of the handgun.
These kits offer enthusiasts the opportunity to learn about firearm mechanics and customization. Their use allows for the personalization of a handgun to meet specific preferences, such as improved triggers or modified sights. Historically, building firearms from component parts has been a practice among gunsmiths and hobbyists seeking greater control over the final product.