In a recent post I was down voted for saying there were fees to 3D printing firearms while others were upvoted for saying I was wrong. I wanted people who may have seen that aware of the laws with sources. Not true. Under the National Firearms Act (NFA), unless it has a rifled bore, a 3D printed firearm is classified as an “any other weapon” and the owner is required to register it and purchase a $200 tax stamp for the weapon. I’m very pro-gun and will be printing a model to make my own in the near future, but this is a serious endeavor. Do the research and be informed when dealing with firearms and their regulations. The best thing to do is contact the ATF and ask all your questions in writing so that they respond to you in kind, so you have a paper trail showing you followed regulations and cooperated with the ATF during the process.Definition of “Any Other Weapon” (AOW): http://ift.tt/2clpaoI to register AOW source: http://ift.tt/2ch7bzm: Lots of valid points about 3D printing rifled bores. Keep in mind the rifling wont last longer than a few shots more than likely. It is a good question and something that should be mailed to the ATF so that when they respond you will have a paper trail showing their clarification on the issue. I personally feel they will reclarify it to be defined as a permanent installation of a bore (metal). A plastic gun with a metal insert bored is another idea put out there that’s interesting. Keep in mind that regardless of rifling there must be enough metal in the firearm to trigger a metal detector for the firearm to be considered “legal” (http://ift.tt/1LorAQ7). AOW is listed as an NFA Firearm: http://ift.tt/2clpe7Q NFA Firearms made require a $200 tax stamp: http://ift.tt/2c8Q6dv is effectively “Some of what you need to know” not “everything”. If you have questions and cannot find an explicit definition or explanation on their website, mail the ATF!Edit2: For those arguing that simply having a smooth bore doesn’t classify a pistol as an AOW I refer you to this ATF document:It is important to note that any pistol or revolver having a barrel without a rifled bore does not fit within the exclusion and is an “any other weapon” subject to the NFA.http://ift.tt/2c1EI1P Page 9 http://ift.tt/2bKrI3K