We have two separate discussions here, and the beginnings of a third.
My understanding (as a layman, and this is not legal advice is):
- making an 80% receiver has no legal ramifications at all — it’s simply a chunk of metal in a special shape — one could sell them as ash trays and they would be completely legal anywhere in the U.S.
- finishing an 80% receiver is legal for anyone who is legally able to own a firearm both where they do the work, and where their legal home of record is
- the specific law on sale is that the firearm cannot have been made with the intention of selling it, but that if it was made without such intent, it would be legal to sell later — however the BATF has closed this “loophole” by aggressively pursuing this “thoughtcrime” and at this time, it looks like the only way to legally transfer a self-made firearm receiver is to make it part of one’s estate, which is the only legal transfer of firearms which is not considered a sale (trading/gifting falls under the same regulations/guidance from the BATF)
- the sear mentioned above is a different thing, it is the key to making a weapon full auto (or with a suitable control group, selective fire) which is a Class III item, and requires paperwork and a tax stamp, which is illegal for anyone to own without having filed said paperwork and gotten approval (requires a background check) and for new manufacture, requires that one meet certain requirements for destination and intent and so forth including having an FFL w/ Class III certification. It is not legal for individuals to own Class III items made after a certain date. Interestingly, felons are exempt from this, since their filing the tax paperwork has been ruled to qualify as “self-incrimination”, which I believe is the ultimate statement on how Byzantine firearms laws have become.
I hope that this frames our understanding of the legality of this thread adequately — to expand on this, we will of course expect that receivers are marked with only two positions — the need for such checks is a further example of why we do not wish to host files (but will accept images and instructions which are clear enough for folks to make their own files from scratch).
Lastly, I will note that some folks have flagged this thread — anyone who doesn’t like firearms should simply skip past it — hopefully we can go back to actual content on the mechanics of finishing receivers and so forth.