80% Builds

Am I Required to Apply a Serial Number to a Homemade Firearm?

serial number on homemade firearm

Building your own AR-15 from an 80% lower has become a popular hobby. Of course, there are many other firearms you can build from scratch as well: everything from a 1911 to a 10/22.

Firearm manufacturing is a highly regulated industry, and everyone wants to stay within the bounds of the law. So, what is, and is not, legal when making your own gun?

In this article, I am addressing one specific question: Do you have to engrave a serial number on your completed firearm?

Read This First

Before I go any farther: I am not a lawyer and have no specialized knowledge of the law beyond what anyone else can research. Nothing in this article should be considered legal advice. To put it in perspective, I’m just a guy with a keyboard – but then, so is that guy on Reddit or Facebook handing out advice. Carefully source your own information.

None of the information in this article applies to state or local laws. It applies only to the federal laws of the United States. Additionally, this information applies only to non-NFA items. All NFA items require serial numbers and other markings.

Laws change. At some point in the future, the laws regarding homemade firearms may change and render this information obsolete. Do your own homework and err on the side of caution.

Am I required to apply a serial number to a gun I manufacture?

Short Answer: No

Long Answer:  My research indicates there is no federal law or regulation that requires a person to mark his or her personally manufactured firearm with a serial number or other information. I had this confirmed by the Firearms Industry Programs Branch of the Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE).

Building an AR from an 80 lower

Additional Information

Federal law does not prohibit an individual from making a fully functional firearm for his or her own use. Further, you do not need a federal firearms license (FFL) to manufacture the gun. Refer to 18 U.S.C. 922 (firearms crimes) and 18 U.S.C. 923 (firearms licensing) in public law. The BATFE acknowledges this here.

However, you cannot make the gun with the intent to sell or otherwise transfer the gun to another. This prohibition includes making a gun as a gift for an immediate family member. However, building a gun for yourself that you later decide to sell or transfer is permissible. I would strongly urge caution, as the practice of making a gun for another is prohibited without a license. It would be up to you to prove that you made it for yourself and then later decided to sell or give it away.

I’ve never been able to find any reference in federal law to a serial number or other manufacturing marks being required on a personally made firearm. When I contacted the BATFE about this in December of 2016, Firearms Enforcement Specialist L. Babbie of the Firearms Industry Programs Branch in Washington DC stated:

Additionally, although markings are not required on firearms manufactured for personal use (excluding NFA firearms), owners are recommended to conspicuously place or engrave a serial number and/ or other marks of identification to aid in investigation or recovery by State or local law enforcement officials in the event of a theft or loss of the privately owned firearm. (emphasis added)

I have never found any credible information that contradicts Specialist Babbie’s statement. Keep in mind this is all referring to federal law – not state law. Individual states may pass laws that require serial numbers on home made firearms.

personally built firearm markings

What about a gun I make for myself and later transfer?

Short Answer: No

Long Answer: My research indicates there is no federal law that requires a personally made firearm that was manufactured for personal use to have a serial number of other marking before you sell or transfer it to another person. However, the BATFE muddies the water on this one because of the way they phrase certain things, and that people do not read the underlying CFR referenced by the agency.

However, when directly questioned about the requirement, BATFE has stated that no serial number is required in this specific case. I suggest reading the additional information below.

Additional Information

This answer is disputed by some gun owners, though it seems clear to me.

Federal law does not prohibit the transfer of a homemade firearm to another person so long as the gun was not made with the intent of transferring it to another person. In other words, when you made the gun, if it was your intention to keep and use it yourself then it is legal to later sell, gift or trade the gun to another person and not be in violation of the manufacturer licensing requirements in federal law.

This information was also confirmed by Specialist Babbie:

A person who previously made a firearm for personal use is not prohibited by law from selling such firearm.  Such seller needs to ensure that he/she is actually selling a firearm that was previously made for personal use and that he/she is not engaged in the business of manufacturing without a Federal firearms license (FFL).

The gun may be transferred in any of the normal ways including face-to-face sales within a state (where not precluded by local law), through an FFL or by passing of the weapons to an heir.

However, Specialist Babbie was careful to note:

Making a firearm to gift to someone is not making a firearm for personal use.

In other words, you cannot make your son a hunting rifle and give it to him for Christmas unless you hold an FFL.

So, since it is obvious that transferring a personally made firearm is legal, let’s address the question of what, if any, marking requirements are there on a gun being transferred. This is where the BATFE causes confusion.

I have been unable to find any public law or CFR that requires a serial number or other marking on a personally made and owned firearm that is later transferred. None.

However, the BATFE makes the statement here that:

Receivers that meet the definition of a “firearm” must have markings, including a serial number. See 27 CFR § 478.92 (Firearm manufacturers marking requirements).

Unfortunately, the BATFE does not link to the regulation for people to review. I suspect that few people take the time to look up 27 CFR § 478.92. But I have and it can be read here.

The regulation states quite clearly:

You, as a licensed manufacturer or licensed importer of firearms, must legibly identify each firearm manufactured or imported as follows…

As someone who is not an FFL holder who is making a gun at home and for your own personal use, this CFR simply does not seem to apply.

I have seen an image of part of a letter that is presumably from the BATFE on this subject that further confuses the subject. In the letter signed by Sterling Nixon, Chief, Firearms Technology Branch, Nixon makes the statement:

…a nonlicensee may manufacture a semiautomatic rifle for his or her own personal use…However, if the firearm is transferred to another party at some point in the future, the firearm must be marked in accordance with the provisions set forth in 27 CFR § 478.92 (formerly 178.92).

Since the words “must be marked” appear, people sometime assume that means the personally made and used firearm that is now being transferred must be marked. However, the full statement includes “must be marked in accordance with…27 CFR § 478.92”, which clearly only applies to FFL holders. In other words, as I understand it, not placing markings on the gun would not take you out of compliance with 27 CFR § 478.92, so long as you did not otherwise fall under the requirements of the CFR.

I confirmed this through a series of e-mails with Specialist Babbie when I asked this question:

For clarification, if I (not a licensed manufacturer or importer) make a firearm for personal use and at some later date I decide to sell it, am I required to have it marked with any information? If so, what information would be required?

Specialist Babbie provided this clear and unambiguous response:

Firearms markings are only required by those who are licensed importers, licensed manufacturers, and those who make an NFA firearm for personal use.  Those marks would be made at the time of import, manufacture, or when an NFA firearm was made for personal use.  Under Federal law, no markings would be required in your circumstance. (emphasis added)

So, with the following information:

  • no law I’ve been able to find or seen cited requiring a serial number or other marking;
  • no CFR I’ve been able to find or seen cited requiring a serial number or other marking; and
  • a BATFE Firearms Enforcement Specialist saying no serial number or other marking is required

it seems fairly clear that no serial number or other marking is required on a firearm that you personally made for your own use that you later decide to transfer.

Again, I urge extreme caution. The presumption in law is that you need an FFL to manufacture firearms for sale to others. It would appear that you need to be able to prove that the personally made gun was for you and used by you and not intended for transfer to another person.

Should I apply a serial number to my gun anyway?

Short Answer: Yes

Long Answer

There are two good reasons why you should consider marking your gun in accordance with 27 CFR § 478.92 even though it is not required. First, it avoids any confusion about the application of 27 CFR § 478.92. Consider this a CYA, though I don’t think it to be a strong enough  reason for me. I have no intention of ever selling, trading or otherwise transferring any gun that I may make to someone else.

The second reason, however, is much more important to me. Marking your firearm with a serial number and other information will allow it to be identified as a stolen firearm if it is ever taken from you. Firearm thefts happen, and a serial number allows local law enforcement to enter the weapon into the National Crime Information Center (NCIC).

When an officer comes across some gang banger with your gun, that serial number will come back as stolen. The thug in possession will go for a felony and the officers might be able to track back and find out who broke into your home. Cops getting criminals – especially violent ones – off the street is something I fully support. A serial number on your gun can help that happen should it ever be stolen.

Was this article helpful?

Researching and writing articles like this one take a lot of time. If you found value in it, would you consider using one of the following links the next time you need to make a purchase? I earn a small amount of money on anything you purchase which literally helps me feed my family.

Additional Documentation

This is the initial e-mail I sent to the BATFE seeking clarification on the issues surrounding the manufacture and marking of personally made guns:



This is the response I received:




I then followed up with this question:




and received this response:



By Richard Johnson

Richard Johnson is a gun writer, amateur historian and - most importantly - a dad. He's done a lot of silly things in his life, but quitting police work to follow his passion of writing about guns was one of the smartest things he ever did. He founded this site and continues to manage its operation.

48 replies on “Am I Required to Apply a Serial Number to a Homemade Firearm?”

Thank you for putting this together. I’ve had the same position on serial numbers, but have been shouted down on Facebook by people who swear (without any documentation) that you must put a serial number of every gun you make. By federal law, this simply isn’t true. Thanks for doing the research for people on this. I wish other gun websites put in a fraction of the work you do.

Thanks. I went to the range today and there was a new person. When I showed him my New Polymer80 pistol he swore up and down that “I am an ex-law enforcement officer and have 20 years experience as a gun smith and it is against the law in Utah to own a pistol without a serial number. It is legal for a rifle or shotgun but not a pistol.” I said oh, can you find that ? All he was able to find was a law that said is if I request the state BCI will put one on for me or replace a damaged number or mark. Then he read it over and over again. See it says you “have to have a serial #” It said nothing of the sort! It said if you ASK them they will PUT one on for you. It also said they have to do it. This is a lot different from saying you have to.
If the teacher sends home a note that says “students can bring their own lunch if they desire” that don’t mean you have to bring a lunch. Then he tried to tell me that the manufacturing rule is 50% and you have to keep careful records of any gun make incase you sell it.
I think he is confusing the laws governing a manufacturer and a home build. One is regulated and the other is not. I think he was just trying to impress his wife/girlfriend. I wasn’t too impressed. I just humored him and left to go shoot my target. At least he didn’t “call the cops”. That could have ended his new job.

So far as I can tell, it is against the law to change, remove, or otherwise alter an existing serial number. Given that *MOST* firearms in possession in America possess a serial number, and a gun that doesn’t is characteristically different in this respect, his logic *ALMOST* works. But just like doctors, there are smart cops, and there are other cops…

Richard- is this page up to date?
Thank you for doing the research and laying this all out. I run into “doubting Thomas’s” from time to time and I use this link to educate them.

“It would be up to you to prove that you made it for yourself and then later decided to sell or give it away.”

I don’t think that’s technically true. If charges were brought against you, the burden of proof would be on the government. Admittedly, there may well be a “guilty until proven innocent” mentality and intent is hard to nail down. So what you said might be closer to actual experience, but it shouldn’t be the case. Ultimately, guilt is whatever a jury says it is. That sentence just struck me as odd.

For what it’s worth, I enjoy your site.

You are correct. People are innocent until proven guilty, the government has the burden of proof for proving that guilt and people should, nevertheless, be prepared for a guilty until proven innocent mentality. It’s unfortunate, but that is where we are seemingly headed.

Thanks for reading and taking the time to comment.


My “American” Experience – at the range with a so-called Polymer80 Legal Expert”

Similar to Brian Winn below, I too went to a local range and proudly displayed my new P80 Compact. It was not my first time building something, I’ve been a 2011 crafter for years, and currently CNC the frames from raw billets. However, this was my first plastic pistola, and I felt it was something I could be proud of. I had done some burn-in testing, and got about 50 or so rounds downrange before a few people started noticing it and we got to talking – ironically about the stigma attached to this type firearm and the craftsmanship required to do a great job.

Just then, a third guy who had been eavesdropping from the adjacent lane (claimed to be a “former” Trooper, one who had recently retired from PA State Police) came over and nearly assaulted me with his outrage, telling me all about how it’s fanatics like me who are arming the gang members and getting cops mowed down in the street.

I had not expected the aggressiveness, and was a bit back on my heels by the attack. So, I acknowledged him politely, thanked him for his years of service as a LEO, and then I asked him for more detail on what he was talking about. And he proceeded to give me a long rant about the illegal ways that people like me were making ghost guns and then selling them on the street, making it impossible for law enforcement to catch anyone or trace the firearm. He demanded to know how I could sleep at night, knowing I was responsible for the loss of lives – even one of his good friends whom he had lost to a ghost gun.

By this time, my two other buds had walked away, shaking their heads. So again – I asked him what he was talking about in reference to what I was doing – specifically. And he yelled even louder about how I was clearly violating both state and federal laws by manufacturing my own guns and possessing guns without serial numbers. He went on to yell about the ways in which the gun industry is highly regulated and completely controlled by the BATFE, and why it’s necessary to fill out both a 4473 and a PSP form in PA to purchase a handgun and his face got beet red as he then challenged me – had I done any of that? Because if I didn’t goddammit, the gun was illegally purchased – that’s a fact!

So, now I was getting concerned because people were noticing this guy’s attitude towards me and I didn’t want to get a reputation for causing trouble at the club. So again, I calmly explained – “But I didn’t purchase this handgun, I made it myself for my own use – so I don’t think any of that stuff you are angry about really applies to me because no transactions or change of ownership took place.” But – He just kept going, even threatened to perform a citizens arrest because I was “committing at least 2 felonies, according to what he already knew, maybe more…” And he headed off towards the clubhouse – supposedly to report me to a club officer. Over his shoulder, he shouted to me that I better be ready for when he returns with someone “in charge around here.”

I left the premises at that point, disappointed in several ways and for many reasons. A couple days later I tracked down a club officer and asked if I had been reported by this guy or had he complained about me. Apparently, he did find the VP, and told him that I had brought a gun I made myself to the range, breaking at least a few laws in the process. The VP is a retired Marine with a chest full of glitter, and doesn’t have much time for BS. He kinda laughed and told him that there’s usually about a dozen or more people doing the exact same thing every week. Then he told him he needed to do some research first, and make sure he understands the law before threatening other members. Apparently the angry guy stomped off and swore he was cancelling his membership.

Look, I don’t mind that he didn’t know what he was talking about. I minded that he used his “position” as a “former” state trooper to lecture me on stuff he didn’t understand, had no jurisdiction on, and had no right to threaten me over. I don’t understand his mentality at all, and especially that only big manufacturing firms can make firearms. In the Philippines, they do this stuff in their backyards with hand-tools and scrap steel – yet produce some near-perfect specimens. Making guns is a completely democratized process these days. There’s no reason anyone can’t do it with commonly available tools, and regardless of these 80% completion setups – they don’t make it possible, they just make it easier.

I found this site via Google, primarily given the current kerfluffle regarding the settlement of the State Department lawsuit over 3D printed ‘guns’ (read Receivers), and the state AGs talking about guns without serial numbers as part of their lawsuit to stop the files from being available. It occurred to me that if a person built his own gun, he could put a unique S/N on it and ID it that way. The other part I was curious about was whether said S/N had to be registered with the BATFE. I wonder if this last step would be a further CYA.

Thanks for reading and taking the time to comment.

Yes, an individual can put a serial number on a gun that he or she built for himself. In fact, I recommend it for the reasons I stated above.

However, it my understanding that it is illegal for the BATFE or any federal agency to maintain a registry of firearms that are not classified as needing a special tax stamp under the 1938 Federal Firearms Act. Of course, it is illegal to make one of those without obtaining the tax stamp first anyway.

State laws are different, and a few states do register firearms. Everyone should check their local laws before buiding a gun to ensure they are not committing a crime.

Thanks again for reading!


First off, thank you Richard for the depth of information that you provided here.

Second, NorEastSida, there is another Federal law that prohibits making or possessing firearms that are not detectable by standard metal detectors and x-ray machines. A 3-D printed firearm would fall under this Federal Statute

Sec 922(p) (1) It shall be unlawful for any person
to manufacture, import, sell, ship,
deliver, possess, transfer, or receive any
(A) that, after removal of grips,
stocks, and magazines, is not as detectable
as the Security Exemplar, by
walk-through metal detectors calibrated
and operated to detect the
Security Exemplar; or
(B) any major component of which,
when subjected to inspection by the
types of x-ray machines commonly
used at airports, does not generate
an image that accurately depicts the
shape of the component. Barium sulfate
or other compounds may be
used in the fabrication of the component.

Curious the date of this article I found a few places that says you need to add a serial number to the lower. Have you found anything saying it is required now? Thanks this article is very nice!

Hi John,

As of the date of your question, I am unaware of any new law that would render the information in this article as obsolete.

As with anything, I encourage you to research the information you find – here and elsewhere – to make your own conclusions. Too much information exchanged online and in gun shops is just plain wrong.



So to my understanding, when placing this serial number on my polymer 80. Could this mean that I could just put a serial number such as my initials plus a few numbers to show that it is for my personal use?

I would love a little bit of clarification and an example if you guys wouldn’t mind. Thank you for your information, I have been reading and continuing to come back to this article.

Thank you,


Hi James,

As I understand the current federal law, no serial number at all is required for a gun that you manufacture yourself for your own personal use. However, if you choose to put a serial number on the firearm (something I am in favor of,) you get to make up any number you like. Your example of your initials and some numbers is perfectly fine. I hope this helps.


Good information. But do you know anyone that have stopped and question about their build from 80%? Let say going to the range. And how to respond to law enforcement? I’ve tried to look for any scenario but could not find any. Thanks

Hi Ryan,

No, I do not personally know anyone that has had an issue with a personally made firearm. I’ve seen “internet stories” about issues, and some of them may even be true.

Assuming you are acting in a reasonable way, the chances are pretty darn slim that you will catch the attention of law enforcement. However, the best things I can recommend are (1) know the law for your jurisdiction (2) cooperate with any law enforcement official in a polite manner and (3) apply a serial number anyway. #3 sort of fits in my CYA of the “Should I apply a serial number to my gun anyway?” part of the article. If you are not required to register the firearm by state law, the no one knows you own/made regardless of what you may have stamped on it. But having it may help avoid any issues in addition to allowing you to report it stolen should your home be burglarized, etc.

Regarding #2, polite cooperation means “don’t be an ass” to the cop. I’m not suggesting you give consent to search your car, etc. Just be a good guy. Best case scenario, the officer appreciates your attitude and you have zero issues. Worst case scenario: you are illegally arrested and the evidence shows you were a friendly citizen making the lawsuit a slam dunk in your favor. Always assume that a jury will be watching & judging your actions – pretend you are on a stage and you want the audience to be sympathetic to you.

I hope this helps.


Awesome write up. I just manufactured a 1911 as a capstone project for my associates degree of science in firearms technology. Being that I manufactured it for my personal use in getting a degree and plinking for a few months I think I will gift it to my father. That should be legal right?

Hi Big Joe,

I’m not a lawyer and I cannot give legal advice. I’d suggest taking a hard look at the responses provided to me by the BATFE and seeing where you believe you fit within them. It sounds like you should be fine, but you are the one that has to make sure you are not violating any laws. I hope that makes sense.



No place did anyone provide a link to the ATF to apply for a Serial Number for a Firearm.
A State will not provide a Serial Number.
For a home built fire arm for personal use no one seems to know. Do you??? Anyone.

No link is provided because no link exists. The BATFE does not issue serial numbers, and God forbid they ever do.
At this time, federal law does not require you apply a serial number to any home made firearm constructed for personal use. If you choose to do so, you choose whatever serial number you like. It is your gun that you made, so give it a serial number that makes sense for you.

To Joe Hammer: The State of Hawaii WILL engrave a serial number (the same number as the firearms registration permit number) if the firearm does not have a serial number.

134-3 (b) Every person who acquires a firearm pursuant to section 134-2 shall register the firearm in the manner prescribed by this section within five days of acquisition. The registration shall be on forms prescribed by the attorney general, which shall be uniform throughout the State, and shall include the following information: name of the manufacturer and importer; model; type of action; caliber or gauge; serial number; and source from which receipt was obtained, including the name and address of the prior registrant. If the firearm has no serial number, the permit number shall be entered in the space provided for the serial number, and the permit number shall be engraved upon the receiver portion of the firearm prior to registration. All registration data that would identify the individual registering the firearm by name or address shall be confidential and shall not be disclosed to anyone, except as may be required:
(1) For processing the registration;
(2) For database management by the Hawaii criminal justice data center;
(3) By a law enforcement agency for the lawful performance of its duties; or
(4) By order of a court.

This is as I read it also, I have often done all of my own legal. It’s simple be polite to the clerk and read 1000 pages of procedures. So I have learned to read as it is written. I have a question that I’m looking for the answer for, cerakote unserialize lowers. Is this something I can do, will a gun Smith be ok with that? Any input would be helpful. I’m a month away from beginning my first build. I have been doing research for about 2 months. Today I shot my first one. I’m building 1 ar15 .300 pistol and 1 ar10 6.5 20″

Hi Peter,

Thanks for reading. I’ve not researched this specific topic, but I don’t see any reasons why all of the standard transfer rules would not apply. I’d recommend contacting a few shops that you might like to have do the work and see what requirements they have. Some shops may have stricter requirements than what federal law requires.


Hey there I’m not sure if you have found the answer to your question yet but I have some information If it helps. Recently I did my first polymer 80 Glock build and I wanted to make sure the lower parts and trigger were installed perfectly so I researched if gunsmiths could install it for me and I found out that they can only work on guns that are serialized. There were many reasons why like if they were robbed or for record keeping etc . So I installed my parts but I kept wondering if it was just right so I called the local gunsmith and asked if I paid him if he could watch me install the parts and instruct me if need be. He said come on down that we could figure out something that didn’t break any laws. I apologize I could have just said that gunsmiths can only work on serialized guns and left my story out. I hope it helps you or someone at some point. And good luck with your build

This is BAD advice from the ATF, and very wrong.
Legal firearms must be serialized or they aren’t legal to possess.
26 U.S. Code § 5861 (i) (page 3)
An 80% receiver does not require a serial number, but as soon as you cut into that receiver and the body is anything but a solid block, it must be searialized to be sold, or to be assembled into a firearm, even for personal use. This is whether you’re operating under NFA or just plain old GCA regs.
Please please please don’t rely on anyone at ATF to advise you on what is legal and what isn’t. If you ask the same question of 5 people at ATF you’re likely to get at least 3 conflicting responses. Ever run across a cop who doesn’t know a specific law? This is the same thing.

Hi Bob,

Thanks for taking the time to respond to my article. However, I think your research is way off base.

You assert that under US federal law firearms must have serial numbers to be legal regardless of who manufactured them or for what reason. To support this claim, you cite two sources: (1) 26 USC § 5861 (i) and (2) a specific portion of an unsigned, undated document found on the US Department of Justice website.

Your first source, 26 USC § 5861, appears to refer only to firearms regulated by the National Firearms Act of 1934. As I state in the “Read This First” section of the article, all NFA items require serial numbers as well as other markings. This law has zero impact on firearms that do not meet the definitions of NFA items such as machine guns, short barrel shotguns and silencers/sound suppressors.

Your second source cites two laws: 26 USC § 5861 and 18 USC § 922 (sections k, o, and v). As I’ve shown above, the first law, 26 USC § 5861, does not apply unless the firearm will be classified as an NFA item which is beyond the scope of the article.

18 USC § 922 needs a little more unpacking. Let’s take each subsection separately.

18 USC § 922 (k) states that it is illegal to ship, transport or receive any firearm that has had its importer’s or manufacturer’s serial number removed, altered or obliterated. The key here is “importer” and “manufacturer.” The definitions of these terms are found in 18 USC § 921. Specifically, 18 USC § 921 (a)(10) defines a manufacturer as “any person engaged in the business of manufacturing firearms or ammunition for purposes of sale or distribution.”

If you are engaged in the creation of a firearm for business purposes, then you are a manufacturer. If you are making one for yourself – you do not meet the legal definition of a manufacturer. Therefore, section (k) does not apply to homemade firearms for personal use. I address this in the article with specific examples.

18 USC § 922 (o) refers to machine guns only.

18 USC § 922 (v) was the 1994 so-called Assault Weapons Ban that was expired nearly 15 years ago. This shows how out of date the information on the US Department of Justice website is.

It is important that you read more than just the individual subsections of law. You have to read the entire law including the definitions sections and any other laws referenced.

I strongly encourage you to do the research and let me know if you find any laws that contradict my research and that of the BATFE.




Do you know how one would register a firearm with BATFE? I’m making an 80% and will be having it engraved with a serial number but can’t seem to find any info on how to register it with them, haha. (Military looking to keep it on base which requires a serial)

Hi Adam,

I believe that it is illegal for the BATFE to maintain a registration of firearms/serial numbers. I would think that as long as you have a serial number of any kind engraved on the receiver that it would meet the requirements of your base regulations.



Richard, I am much like you as I enjoy researching in depth requirements, rules and laws pertaining to things of interest to me – such as putting up a flag pole for a US flag in a HOA subdivision. So I appreciate the length you have gone thru in your excellent article. While I was in a gun shop recently I was asking if they had firearm engraving equipment and what they would charge to engrave my home made AR with a s/n that I would provide to them. They balked somewhat saying for them to take in a firearm for work they would need to prepare paperwork to accept a firearm for gunsmithing and that paperwork required a s/n (which I did not have, so they could accept the gun but could not legally return it to me??). During our discussion they also (the 2 store owners, 1 customer in the store, plus 1 sheriff out of uniform) said a homemade firearm could NOT be transported across state lines w/o a s/n. They said even tho it is legal to build a homemade firearm that that firearm could not legally cross state lines and if I tried to take the gun in my vehicle from one state to another and was stopped for any reason and the LEO found that I had a gun w/o a s/n and my drivers license showed I was from another state than where I was stopped, that I would most likely be arrested. I could find no evidence supporting that statement. Have you heard of anything like that? Again I appreciate the effort you put into your article.

Hi Robert,

I have not seen any law about that. There are laws about the transport of SBRs, sound suppressors, machine guns, etc. across state lines – and that may be where their confusion comes in.

However, each state has a different set of laws, so entering a new state with the unserialed gun may be illegal because that state has its own law that prohibits such an item.

If you discover anything different in your searching, please come back and let us know!



I built 2 Glocks from Polymer 80 and being a fanboy I bought OEM Glock slides off eBay to complete the build. My question is does the fact that my slides and barrels have serial numbers confuse the fact than my receivers are not serialized? Those serial numbers probably belong to a lower somewhere but not mine. Would it be a bad idea to engrave those same numbers on my lower?

I see no reason why you cannot use the serial numbers on your slide/barrel as the serial number on your receiver. Serial numbers should be unique to a manufacturer/model, but whatever Glock-compatible gun you’ve built is not a Glock so there should be zero problems with using the same number. For example, the same six-digit serial number might be found on a Taurus pistol, Alpine car amplifier and a Black and Decker drill. Just make sure that you tell anyone who comes in contact with the serial number (an FFL, law enforcement officer, or whoever) that the gun is not a Glock but a homemade gun. Of course, this is not legal advice, just my thoughts on the matter.


Say I was going to serialize a Glock polymer 80 for personal use what needs to be included besides a s/n do I need my name city state caliber or just a number.
Thank you

It amazes me how many people don’t read the article and just jump to the comments section to ask questions you clearly answered in the text. SMH

Hey! so i read all the information provided such as the same questions that were ask plenty of times.. although my #1 question is can i take my no serial number HOME MADE FULLY STOCK AR pistol and glocks to the range legally? I live in CA

I’m afraid I have not researched California laws. I have been told that all firearms – including home made guns – need to have a serial number in California. I’d recommend checking with the guys at CalGuns.


What about the number of guns you can manufacture for personal use? I have not found anything on that. I have heard from local anodizing places that they will only finish one un serialized lower per person. Claiming a felony if you have more than one un serialized gun. Claims they have talked to the ATF about it before.

Hi Kevin,

I’m not an attorney and this is not legal advice. I’ve not seen any federal law that states you can only have one homemade firearm. I suspect there is no bright line rule or law about that, but can’t say for sure. Often, BATFE inspectors don’t know the laws very well. When they arrive at a dealer/manufacturer location, they are there to count forms and look for paperwork irregularities. While I am not trying to disparage them, many of them simply don’t know the laws surrounding gun ownership – especially when it comes to home made firearms. Their expertise is in paperwork and inventory control.

Again, this is not legal advice. Nor am I attempting to address state laws. Those can vary widely.

I hope this helps.


As I read this, if I fill out a Form 4, submit $200 and get ATF approval (and apply a s/n), I could then build, for personal use, an NFA weapon.

I personally know a man who did this for a suppressor.

My question is: would this also apply to a machine gun or drop-in-auto-sear?



Hi Ray,

I am not an expert on the NFA nor am I a lawyer. My understanding is that you can make an SBR or suppressor with the proper tax stamps but you have to be careful in the order on how you do it. In other words, you can’t make it and then apply for a stamp.

On full auto/select fire stuff, I believe the Hughes amendment applies. Specifically, 18 USC 922 (o)(1) makes it illegal for anyone to possess a machinegun. The exceptions are given in 18 USC 922 (o)(2) which allows for possession/transfer by government entities and possession/transfer of machineguns that existed at the time the law went into effect in 1986.

So, unless you are a federally licensed manufacturer of machineguns, I do not think there is any lawful ways of obtaining or making a full auto/select fire firearm that was made after 1986.

Like I said – I’m not an NFA expert nor an attorney. I would encourage you to seek out an experienced attorney if you wish to explore this further.

I hope that helps.


Thanks for writing such a well-researched and helpful article, sir.

What about this hypothetical situation: Say a family member who has an FFL builds me a rifle with a custom-milled (proper term?) billet lower, and they say that it will not come to me with a serial number. Would I be putting their FFL at risk if I don’t insist on the lower having a serial # at the time of purchase, or could I just add my own after the sale and still be kosher?

The article suggests that they could potentially sell me one of their many, many personal rifles (or just the lower from it?) and avoid the whole issue (built for personal use and then transferred). Do you think that would apply to someone with an FFL?

This article has an excellent shelf-life. Thank you for continuing to respond to comments and questions so long after publishing!

Thanks for the questions. Let me emphasize that I am not an attorney and the BATFE could change its opinion at any moment.

I believe that anyone who builds a gun for anyone else (as you described) is required to have a manufacturing license and serialize every receiver. My understanding is that if the person does not have a manufacturing license and serialize the part, it is a federal crime.

If a person, outside of their business which the FFL is issued to, manufactures a firearm for personal use and then at a later date decides to transfer the gun, I believe that would be legal. The BATFE, however, might make a case out of whether the gun was actually made for the manufacturer’s personal use and then later transferred and not a case of giving you one and then making another to replace it. I suspect they would argue that would be functionally the same as making it directly for you.

Like I said – I am not an attorney. I’d argue that if you are not buying one to make for yourself, just buy a stripped lower. They are not expensive and can still be found.

I hope this helps!


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