We are really just attempting to nail down without a shadow of a doubt what the ATF is declaring, and they are always intentionally vague. An AK would start at the actual end of the receiver, so the AR would to is what you are stating. Like I said earlier, that was not my understanding of it, and if I am wrong then so be it. It's not the first and certainly will not be the last time.
I'll get overly concerned as soon as I see a guy with an ATF hat coming up to me with measuring tape at the range I guess.
The word for word is; "Conversely, it is inappropriate to include a folding "stabilizing brace" accessory in the overall length measurement of a firearm because, unlike a rifle or shotgun, a stabilizing brace is not an element of either a statutory or regulatory definition of any firearm."
So adding a folding mechanism to a brace, that was not created AS a brace with a folding mechanism built in (Like the FS1913 by SB) is creating something technically unspecified in the letter.
https://live.staticflickr.com/65535/...5a21f67471.jpgATF-folded-brace_Redacted_Page_1-768x1096 by
Willis, on Flickr