https://www.federalregister.gov/d/2022-08026/p-840
(c) Partially complete, disassembled, or nonfunctional frame or receiver. The terms “frame” and “receiver” shall include a partially complete, disassembled, or nonfunctional frame or receiver, including a frame or receiver parts kit, that is designed to or may readily be completed, assembled, restored, or otherwise converted to function as a frame or receiver, i.e., to house or provide a structure for the primary energized component of a handgun, breech blocking or sealing component of a projectile weapon other than a handgun, or internal sound reduction component of a firearm muffler or firearm silencer, as the case may be. The terms shall not include a forging, casting, printing, extrusion, unmachined body, or similar article that has not yet reached a stage of manufacture where it is clearly identifiable as an unfinished component part of a weapon ( e.g., unformed block of metal, liquid polymer, or other raw material). When issuing a classification, the Director may consider any associated templates, jigs, molds, equipment, tools, instructions, guides, or marketing materials that are sold, distributed, or possessed with the item or kit, or otherwise made available by the seller or distributor of the item or kit to the purchaser or recipient of the item or kit. The following are nonexclusive examples that illustrate the definitions:
Example 1 to paragraph (c)—Frame or receiver: A frame or receiver parts kit containing a partially complete or disassembled billet or blank of a frame or receiver that is sold, distributed, or possessed with a compatible jig or template is a frame or receiver, as a person with online instructions and common hand tools may readily complete or assemble the frame or receiver parts to function as a frame or receiver.
Example 2 to paragraph (c)—Frame or receiver: A partially complete billet or blank of a frame or receiver with one or more template holes drilled or indexed in the correct location is a frame or receiver, as a person with common hand tools may readily complete the billet or blank to function as a frame or receiver.
Example 3 to paragraph (c)—Frame or receiver: A complete frame or receiver of a weapon that has been disassembled, damaged, split, or cut into pieces, but not destroyed in accordance with paragraph (e), is a frame or receiver.
Example 4 to paragraph (c)—Not a receiver: A billet or blank of an AR-15 variant receiver without critical interior areas having been indexed, machined, or formed that is not sold, distributed, or possessed with instructions, jigs, templates, equipment, or tools such that it may readily be completed is not a receiver.
Example 5 to paragraph (c)—Not a receiver: A flat blank of an AK variant receiver without laser cuts or indexing that is not sold, distributed, or possessed with instructions, jigs, templates, equipment, or tools is not a receiver, as a person cannot readily fold the flat to provide housing or a structure for the primary component designed to block or seal the breech prior to initiation of the firing sequence.
According to the modified rules, mere possession of an 80% lower and the jigs, templates, equipment, or tools necessary to complete the lower is considered to be a firearm,
regardless of whether the jigs and the 80% lower were sold as a kit or purchased separately at different times.
It is my interpretation of the above rules that if you've ever bought an 80% lower that included a jig and you still have the jig, then every single 80% lower you buy from that point on is a firearm even before it is completed.