Silver Lifetime
- Messages
- 743
- Reactions
- 2,361
An 80% build is where the lower receiver, the serialized part of an AR15 (where the trigger is housed and the magazine is inserted), is sold as an 80% complete kit, which does not require a background check because it is not a "firearm". The purchaser then uses machine tools to finish the last 20% of the lower receiver, such as milling out the pocket for the trigger and firing mechanism. This creates a finished lower receiver which can then be built into an AR pistol or rifle without a background check. Currently, it is legal to build your own firearms for your own personal use and an 80% kit allows that. While ARs are one of the most common 80% kits, you can also get them for Glock platform pistols, 1911 style pistols, etc. Most of these kits utilize a separately purchased jig to act as a guide to completing the receiver/frame/etc.What is an 80% build?
Example of an 80% AR-15 lower receiver. Note the solid aluminum area where a fire control group would fit:
An example of a lower receiver, jig, and router as a kit. The router is used to do the machining, but more professional machine tools are strongly recommended:
For comparison, here is a 0% complete receiver:
Last Edited: