I was aware of all that and the last I heard you could get in deep [bleep] by shouldering one.
The ones coming out of Sig (with their arm brace attached at the factory) come with a copy of a letter from the ATF stating that how you shoot it doesn't alter its designation as a non-NFA firearm. The letter even gives the example of shouldering it as not altering its designation.
Which the ATF later recanted its statement and issued an opinion letter saying it does now make the gun an NFA item if shouldered.
Nope. A recanting has to specifically refer back to the original letter, stating that a rule has been altered or reversed. The second letter doesn't do that, but merely expresses a differing opinion on the part of someone in the same office. Since there is no statement published to the general public by that office addressing this matter, one may rely on either letter, or ignore them both completely, relying instead on the law as written, which only prohibits shoulder stocks, and doesn't specify which ways one may shoot their non-NFA firearms. The ATF has already classified the Sigs as non-NFA, even with the arm braces installed at the factory, which is why store personnel don't get arrested for selling them absent NFA paperwork. There is no precedent in the law for a manner of shooting an unaltered firearm altering its NFA/non-NFA designation.
