Frame or Receiver

Can you define a firearm “frame or receiver”? 
Do you think it is the “part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel”? 27 CFR § 478.11. 
If you answered yes, then a strict construction. . . er. . . ‘inflexible’ application of said definition “could mean that as many as 90 percent of all firearms (i.e., with split frames or receivers, or striker-fired) in the United States would not have any frame or receiver subject to regulation.” 2021R-05F, 5. Put another way, each and every part of 90% of the firearms sold in America could be sold, alone, over the internet, without background checks. 
“Holy underwear! [90% of firearms do not have a frame or receiver subject to regulation!] We have to protect our phoney baloney jobs here, gentlemen! We must do something about this immediately! Immediately! Immediately! Harrumph! Harrumph! Harrumph!” Blazing Saddles (Crossbow Productions, 1974).

The Problem.

In 1956 the AR-15 was designed by Eugene Stoner, and he promptly applied for a patent. In 1960, a patent was issued. In 1968, Congress passed the Gun Control Act regulating firearms and including in that regulation “frames or receivers” of firearms. Sometime shortly thereafter the Treasury Department, in charge of implementing these regulations before the creation of the modern ATF, wrote the current definition of “frame or receiver” basing the determination off of three or four characteristics. 

No one noticed that this new fangled rifle being used by the military in ‘Nam didn’t have a frame or receiver as defined. (Of course, neither did the 1911 pistol; a design more than 50 years old at the time.) 

Nearly 50 years after adopting the definition, some courts realized that persons manufacturing lower ‘receivers’ for AR-15s were not actually making regulated “frames or receivers.” See United States v. Rowold, 429 F. Supp. 3d 469, 475-76 (N.D. Ohio 2019). (“The language of the regulatory definition in § 478.11 lends itself to only one interpretation: Namely, that under the GCA, the receiver of a firearm must be a single unit that holds three, not two components: (1) The hammer, (2) the bolt or breechblock, and (3) the firing mechanism.”); see also United States v. Roh, 8:14-cr-00167-JVS, Minute Order p. 6 (C.D. Cal. July 27, 2020); United States v. Jimenez, 191 F. Supp. 3d 1038, 1041 (N.D. Cal. 2016). These Courts enforced the law as written. The ATF lost.

What do you do when you lose?

Re-write the rules. 

Having 50 additional years to figure out the 1911 design, 111 years in total, the ATF set out to write a definition of “frame or receiver” that accurately included what was commonly understood as the frame or receiver of that firearm and many others. The ATF’s initial try overshot the requirements. Instead of accurately defining a frame or receiver of each gun, they wrote an over inclusive definition and caught multiple parts of each firearm. Enforcement would be a logistical nightmare. 

In typical leftist negotiating style, after demanding an arm and a leg, they reconsidered and settled for only an arm. Aren’t firearm owners lucky? 

The New Definition

After 50 years of relying on a mere 30 words to define “frame or receiver” the Biden administration updated the definition to 16 pages including sub-definitions, examples, and grandfathered classifications. We’ll start with just the core of the new definition.

(a) Except as otherwise provided in this section, the term “frame or receiver” means the following—

(1) The term “frame” means the part of a handgun, or variants thereof, that provides housing or a structure for the primary energized component designed to hold back the hammer, striker, bolt, or similar component prior to initiation of the firing sequence (i.e., sear or equivalent), even if pins or other attachments are required to connect such component to the housing or structure. 

(2) The term “receiver” means the part of a rifle, shotgun, or projectile weapon other than a handgun, or variants thereof, that provides housing or a structure for the primary component designed to block or seal the breech prior to initiation of the firing sequence ( i.e., bolt, breechblock, or equivalent), even if pins or other attachments are required to connect such component to the housing or structure. 

27 CFR § 478.12.


The first thing you may notice is that now “frame” refers to handguns and “receiver” to rifles and shotguns. What term do you use for a rifle, such as an AR-15 or an AK-47 that may also be offered as a handgun? Or for a handgun, such as a Glock or a broom handle Mauser that may be equipped with a stock and turned into an SBR? You use the term for the dominant variation and consider the alternatives simply “variants thereof.” (That is subpart (3) in case you are wondering.)

The second difference is that each is characterized by providing “housing or a structure” for a “primary [energized] component.” This key characteristic is much more flexible than the existing definition of frame or receiver. 

Finally, to hammer home the flexibility, the definition notes that the necessity of pins or other attachment requirements do not negate that the item provides housing or structure.

This definition ought to capture some piece of any firearm designed.  (Bonus point to anyone who can design a firearm with no frame or receiver using this definition. Suggestion: a slam-fire design with no component to hold the bolt open and no magazine feed to avoid the definition of machine gun.) 


The new definition, if applied to existing designs, would change the designation of frame or receiver in some instances. As a prime example, under the new definition the upper receiver of an AR-15 is the receiver. The lower is just another part that does not fit the new definition of receiver. 

This presented a problem. There are tens of millions of existing, un-marked upper receivers in private hands. If ATF enforced the rule without allowance for past practices, manufacturers would have to mark upper receivers rather than lower receivers. New AR-15s would ship with unmarked lowers and lowers could be bought and sold as any other unrestricted part.  Any Tom, Dick or Harry could combine existing unmarked upper receivers with newly manufactured unmarked lower receivers to make a “ghost gun.” The number of untraceable firearms would explode. 

An allowance had to be made for consistency sake. As an accommodation, the definition applies literally only to new designs going forward, and existing designs are grandfathered to include as the receiver or frame the part that is already understood as the receiver or frame. Such allowance included AR-15s, Ruger Mark IV pistols, Benelli 121 M1 shotguns, and box-type machine guns. 

The 80% Lower

A key purpose of this rule was squelching the supply of partially complete frames and receivers known as 80% lowers or frames. To that end, ATF created a definition specifically to catch these and the kits sold with them and included five examples for our erudition.

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.

Even the ATF knew the above definition was less than clear, perhaps intentionally. To illuminate, the regulations now include examples of the appropriate application of the new definition. Let’s take a look at each.

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.

This is the classic 80% lower kit. A partially complete lower with a jig or template is now a firearm. If you can purchase both together, then a background check must be conducted if sold by an FFL. Lack of instructions is not enough to remove these items, combined, from the definition of frame or receiver: instructions can be readily found and accessed online by most anyone.  

The only other condition found in this example is the ability to “readily complete or assemble” the frame with “common hand tools.” If the frame requires significant work to complete, or if an expensive machine is necessary, then this example would not be applicable and we would have to look further to determine if a particular combination of items is a firearm 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.

Similar to the example above, a partially complete frame with templating included is a firearm.  Consider the template or index markings as a built in jig. It guides a person in readily completing the frame with common hand tools.

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.

This particular example gives much frustration. While not of particular concern with modern manufactured firearms, after all who would destroy a firearm just made, it does affect historical items ‘de-milled’ prior to importation into the country. Consider WWII machine guns imported for parts and collecting purposes. The ATF approved method of de-milling has changed over the years from simple band saw cuts to torch cuts in three places. 

“Paragraph (e)” does not include any method that leaves a recognizable portion of the receiver. (A very important trait for anyone assembling a dummy firearm.) It is now possible to have an unregistered machine gun that is nothing more than a frame or receiver previously de-milled to ATF specifications. This changes the goal post and leaves unsuspecting innocent individuals with a felony possession.

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.

Perhaps the most interesting effect of this ruling can be seen in juxtaposing Example 1 and Example 4. The same exact piece of metal can be either a firearm frame or receiver or just a piece of metal depending on what is possessed with it. In effect, manufacturing a firearm can now be accomplished by acquiring or combining multiple items without actually changing any of those items!

Companies may still sell AR-15 billets or blanks, as long as they do not offer any jigs, templates, tools, or instructions to go along with those blanks. 

What about companies that sell jigs, templates, tools, and instructions but no billets or blanks? Will there be a market for kits that are compatible with another company’s billets and blanks? Most likely this will be the new method of selling kits. The two companies cannot work together because that would be a conspiracy to sell firearms without a license. But nothing stops them from working independently. 

Could the ATF take the position that a kit with a jig, instructions, templates, and tools, without any blank or billet to form into a frame or receiver, is already a firearm? If true, would any machine shop be a firearm? What about CNC machines? This position seems untenable. And the key component to such kits is information: the dissemination of which is protected by the First Amendment.

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. 

This Example is the same as above with the slight difference that the bending of the flat blank is offered to provide an example of what is not “readily” accomplishable. The same would be true for building frames for Sig 320s.

Kudos to you if you noticed the word “readily” used in the definition and within these examples. This seems to be the key characteristic upon which the ATF relies in determining when an item becomes a firearm. Once the item can be ‘readily’ completed to function, it is a firearm. 

So what does “readily” mean? 

Readily. A process, action, or physical state that is fairly or reasonably efficient, quick, and easy, but not necessarily the most efficient, speediest, or easiest process, action, or physical state. With respect to the classification of firearms, factors relevant in making this determination include the following: 

(1) Time, i.e., how long it takes to finish the process; 
(2) Ease, i.e., how difficult it is to do so; 
(3) Expertise, i.e., what knowledge and skills are required; 
(4) Equipment, i.e., what tools are required; 
(5) Parts availability, i.e., whether additional parts are required, and how easily they can be obtained; 
(6) Expense, i.e., how much it costs; 
(7) Scope, i.e., the extent to which the subject of the process must be changed to finish it; and 
(8) Feasibility, i.e., whether the process would damage or destroy the subject of the process, or cause it to malfunction. 

27 CFR § 478.11. Eight characteristics are packed into that one word. And not a single one is objective. There will certainly be room for argument when applying this definition in the real world. 

To the ATF’s credit, they looked to court cases for how to interpret the meaning of readily. Unfortunately, the ATF did not consider that the average person applying this definition is not a Federal Judge selected for their legal renown. 

This definition will either leave regulated entities at the mercy of the ATF to determine when an item becomes a frame or receiver, or encourage litigation by those persons with enough resources (or perhaps enough at stake) to take on the ATF. It does not provide the type of clarity for which one hopes. 

Where do we go from here?

Some form of incomplete firearm parts will still be available for sale and not subject to regulations as a firearm. The level of completion may or may not change. The practice of selling parts with those tools that help a layman finish the parts will necessarily cease. However, I expect there will remain a ready market for parts alone and for tools without any item that could be made into a firearm. 

Future builders are likely to place a major emphasis on 3D printing and handguns with plastic frames. These items will be the most difficult to prevent people from making at home. The ATF had to admit that raw, liquid plastic is not a firearm. With that material, and ever more available 3D printers, private citizens will be able to print firearm frames and receivers at home. 

The cat-and-mouse game of bringing firearm manufacturing to the public will continue, and technology is not on the Government’s side.

In the meantime, I suggest being cognizant of possessing instructions, templates or jigs, and unfinished receivers for what could be a machine gun. Under the new regulations, combining a pipe with a Sten receiver template is the making of a machine gun. 

Outside of counterfeiting, it’s never been so easy to print a felony. (Do you know the outside diameter and wall thickness of your galvanized fence post?) Be careful, and if I can help you navigate some legal question, do not hesitate to reach out.