Nope. No requirement to notify. Also, the ATF does not confirm when you request removal from the registry.
I sold a SBR this year. I had a nice long conversation with the ATF prior to the sale as well as a couple of NFA lawyers.
He is wrong. There is no requirement to notify the ATF if I sell a SBR in non SBR configuration. If you return it to SBR configuration you are have committed a felony.
Not true. Without a SBR uppers on the lower, it is nothing more than a lower.
I could give you one of my SBR lowers tonight as long as it doesn't have an upper shorter than 16" on it when I do.
You want quiet you gotta go with an UZI. I'm interested in seeing how the Scorpion compares to the Uzi suppressed. I may dump my 9mm AR SBR setup at some point in the future. I never shoot it.