...never mind, he updated the listing or I was not reading. It is still two stamps though.
You could get any other m16 or configuration and set it up that way for a cheap deal of $10k-25K and a stamp depending on what you get.
Or just become a SOT.
Another question for those that use to carry one, did the originals have a serial number on the sound moderator like that? Wondering if it was added at a later date to meet some ATF reg. or if it is original.