Looks like the BATFE updated their website, and in the process didn't forward any of the links from their old content to the new URL format, bad web development!
But I digress.
I wanted to take this as an opportunity to update my links, as well as expand on some of the topics discussed in my earlier post about the legalities of building your own firearms. Namely, can you sell a home built firearm without a serial number?
Do you need to add a serial number to a home built firearm?
So, is there a law that says its legal for someone to build their own firearm, then later decide to sell it without a serial number? It's a little more complicated than that, and it involves unicorns.
Proving Unicorns Don't Exist
Laws are a lot like unicorns when you really think about it.
Stay with me for a moment.
Without the rule of law people are free to do anything they want. There are no restrictions. Laws can only prohibit actions, they never enable actions.
Under the rule of law, we can make things illegal. For example, its illegal to throw a frisbee on the beach in Los Angeles county. (crazy, right?) But what about making the trip to Orange county and throwing the frisbee there, is that legal? Yes, because there is no law prohibiting it. The purpose of laws is to prohibit actions, not to grant permission for actions.
So what about unicorns? Proving that unicorns don't exist isn't possible (that's not how the scientific method works). We could prove, however, that unicorns do exist if for example we found a live unicorn in a remote Amazon jungle. Hard evidence.
Just like laws.
Remember, laws only prohibit actions, they don't grant permission for actions. We can't show there is a law granting permission to sell a home built firearm without a serial number (that would be proving unicorns don't exist). But what we can show is that the there is nothing in the law prohibiting home builders from selling firearms without serial numbers.
The law detailing how firearms must be identified is 27 CFR 478.92.
However, this law only applies to licensed manufacturers. Remember home builders (non-licensed individuals) are people building firearms for their personal use, without the intent to sell them. The law does not apply to non-licensed individuals building their own firearms. Here is the title of 27 CFR 478.92, note that it only applies to licensed manufacturers.
§ 478.92 How must licensed manufacturers and licensed importers identify firearms, armor piercing ammunition, and large capacity ammunition feeding devices?
Further, reading through the full text of the law, you'll note that there are no requirements for non-licensed individuals to engrave anything on firearms they build. There is no law requiring home builders to add a serial number to their home built firearms.
Selling a Firearm Without a Serial Number
A fairly prevalent and completely false internet rumor is that an individual can't sell a firearm unless it has a serial number.
That's not true. In fact, the BATFE Form 4473 used for firearms transactions has specific instructions for what to do in the event the firearm being transferred does not have a serial number.
The 4473 has instructions for Section D, Block 28 (serial number) printed on the form, it reads:
Should you acquire a firearm that is not marked with a serial number; you may answer question 28 with "NSN" (No Serial Number), "N/A", or "None."
Pretty straight forward. A firearm made by a home builder without a serial number can be transferred just like any other 4473 transaction.
I hope that adds some clarity to the issue, and shows that a home builder can make (without the intent to sell) a firearm without a serial number. However, if they decide to later sell it, it can be transferred just like any other firearm.