So basically you can use up to 10 parts to make a firearm if you didn't want to build the whole thing? Similar to the 51% rule in aviation?
You can use as many off-the-shelf parts as you want for any "sporting" firearm, and as may
domestically produced parts as you like in any firearm. What that text refers to are provisions of section 922, which prohibit the importation of non-sporting firearms. That is why you see some goofy re-works of rifles like the thumbhole stock Norinco AKs and the HK SL8, which is the importable version of the G36. There are scores of folks who are in violation of 922(r), mostly because they didn't know about it, and started swapping out parts in their SKS or Romanian WASR AK. It is not something that is heavily prosecuted; ATF just doesn't seem to care about the 19 year old kit who covered his Yugo underfolder in Tapco parts, but still has an import parts count of 11.
Simply put, if you are building a "non-sporting" firearm, such as a conventional pistol grip AK, AR, G3, CETME, FAL, etc, on a receiver YOU manufactured (legally, the receiver is the gun), then you must have 10 or fewer
imported parts (optics, lights, lasers, etc. are accessories, not considered gun parts). Same rules apply if it is an imported receiver. If it is a USA produced,
finished & serialized commercial receiver, however, the import parts count is irrelevant, as it is declared a domestic firearm. That's the deal with the parts kits that are everything but the receiver; the receiver is non-importable (oftentimes because the receiver is a machine gun receiver, and even if you were to weld up the extra cuts & holes, ATF has the "once a machine gun, always a machine gun" policy)
If you are building a "sporting" firearm (basically an arbitrary, "lick your finger and check the wind" set of features ATF declared), then import parts count is irrelevant.
The tax thing and approval from ATF kinda sucks but those are for Title2 stuff right?
Yes, the $200 tax stamp applies only to title II NFA stuff (short rifles/shotguns, destructive devices, supressors, AOWs). To make a title II weapon, you complete a form 1, get your local CLEO (sheriff or chief of police) to sign off, mail the form and a $200 check to NFA branch, then wait for approval (has been quicker lately, but was taking over a year at times). The part about machine guns is due to the Hughs amendment to the 1986 Volker-McClure act, which prohibits the transfer of machine guns made after May 1, 1986 to private citizens. That's why machine guns are so expensive these days; fixed supply, increasing demand. There are somewhere around 174,000 transferable machine guns on the registry. The only work-around is to become an SOT manufacturer, who can build and possess "post samples". But being an SOT is not the same as being a "kitchen table FFL", and the machine guns must be transferred or destroyed if the license is not renewed or otherwise becomes invalid.
Title 1 can be 100% manufactured by anyone is isn't a felon and don't need to be checked or registered or anything. How awesome is that!?
It isn't just felonies; domestic violence conviction, misdemeanors that could have carried a sentence >12 months, being adjudicated a mental defect, having warrants or being a fugitive. All the same stuff that's listed on the form 4473 when you buy a gun from a dealer.
But yes, if you can lawfully possess a firearm, you can lawfully build one for yourself. You do not have to serialize it, and it
is legal to sell home builds; you just can't build them with the
intent to sell. Kind of a fuzzy line, but basically, the guy who sells a home build years after making it is in the clear, where the guy who bought and finished a 2 dozen 80% lower receivers, built them, and has been selling off complete rifles to generate an income is in violation of the law.
As for the 80%, again, ATF has kind of an arbitrary declaration of what constitutes 80%, but they are not legally a firearm until they are 81% or more complete. That is why you see AR-15 80% receivers sold with no FFL requirement; they're legally a paper weight until you start cutting on them.
Just wondering, is there a HMEM equivalent to the gun making/smithing world you hang out at or could recommend?
I think Practicalmachinist.com has a pretty busy firearms section, but otherwise I don't know of any boards.