Machining an 80% lower into a stripped AR-15 lower receiver may seem the same as 3D-printing a firearm. But are these two gunsmithing projects the same? Short answer: No. Long answer: Sort of. Let's break it all down. The 80 lower receiver vs. the 3D-printed firearm: What's the difference? Find out below!
#1: The 80 lower receiver is not a firearm
No one can claim the 80% lower is a firearm and be correct. Until machined, an 80% lower is a hunk of aluminum or polymer that resembles an AR-15 stripped lower receiver. To the ATF, it's no different than the roll of aluminum foil in your kitchen pantry.
Some retail outlets (Amazon and eBay) have banned the sale of 80 lower receivers. Those company policies do not set any legal precedent for calling an 80 lower receiver a firearm. Only once you machine an 80% lower into a stripped AR-15 lower receiver with an 80% jig does it become a firearm.
#2: An incomplete, 3D-printed firearm could still be a firearm
The moment you upload a firearm schematic to a 3D printer and press "start", you're now building a firearm at home. Even if a 3D-printed firearm isn't 100% complete, it could still be legally defined as such. This could land you in hot water if you're building a firearm that might be considered illegal in your state.
The ATF has spelled out what defines an 80 lower receiver vs. what defines a stripped AR-15 lower receiver. Because of this, 80 lower receivers are built and sold to ensure they're not classified as such, until the buyer machines it.
But 3D-printed firearms can be printed in different ways. Because of different build schematics, it's possible to partially 3D-print a firearm that could be made functional in some way. We therefore strongly recommend you do not start printing a firearm using a 3D printer until you're confident you're operating within the confines of the law.
#3: Don't 3D-print an 80 lower receiver until you're ready to build
The above risk holds especially true if you plan on fabricating a polymer 80 lower using a 3D printer. The ATF has classified 80 lower receivers as non-firearms because the fire control group is filled in, no holes are drilled, and no components can be installed to make it partially functional. If you partially 3D-print an 80 lower receiver but don't complete it, the unfinished lower could be classified as a firearm even still.
#4: 3D-printed firearms are under legal scrutiny
Currently, it is legal to buy, own, and build an 80 lower into a stripped AR-15 lower receiver (at least one form or another) in all 50 states. Some states require serialization and other applications, but you're generally safe to build.
Unfortunately, 3D-printed firearms don't get the same treatment. Just recently, the Maryland House of Delegates gave approval to outright ban 3D-printed firearms. Many other states are also considering legislation banning the practice.
#5: 3D-printed firearms cost more to build than 80 lower receivers
Currently, the most affordable 80% lower and jig kit comes in at just $75, thanks to Polymer80's G150 Phoenix2 kit (available in black or Flat Dark Earth). The kit includes an 80 lower receiver, 80% jig, and the necessary tooling to build it. Most 3D printers that can produce a 3D-printed firearm start at $300 and quickly climb over $1,000, up to $12,000.
If you're considering a 3D printer to build multiple lowers or firearms, take a pause. We now offer 80 Lower Jig Combo Kits that include multiple lowers, like the Freedom Combo Kit. This kit includes on AR-9, AR-15, and one AR-10 80 lower receiver! You can build a different configuration and even different calibers (like 300 BLK and 9mm). The 80 lower receiver provides a more affordable alternative to building a firearm at home when compared to doing so with a 3D printer. Given the national legal uncertainties also surrounding the practice of 3D-printing firearms, we advise against making an investment in the 3D-printed gun hobby at this time."