The problem is there's nothing to really go by on domestic demils or demils for importation, LOTS of suggestions and "spooky language" but no REAL manual/illustrations that I'm aware of, as long as govt does that they CAN change rules overnight, and they clearly have done so. FTB letters are notorious for being reversed on a whim.
Fed (friend of mine) led me to ATF's website many yrs ago, where there used to be a PDF illustration on ATF's website concerning "bandsaw" receiver cuts. Raids ensue at IO and many others, we both noted this PDF demil guide was changed to "torch cuts ONLY" over a few days, I reviewed the torching diagrams and noticed a variance in where they were cut, along with some disclaimer BS (their wiggle room?) about NOT exact cut locations, 1919/G-3/FAL was there for sure. Wouldn't you know it, right after door knocking and mass confiscations started (IO, Dan's, etc) the demil links were no longer found, "file error, file not found".
Hmmm...now why would they do that, while at the same time grabbing up parts kits and raiding vendors? Might be used against them, that's why, I really wish I'd copied those PDFs, so do a few others.
This whole confiscation issue could've resulted from mis-communication on demil process, perhaps a careless agent's inspection, I kinda doubt it, what I have seen (hundreds of times) are rules changed within days to suit their agenda. What we need is a clear and basic guideline devoid of lawyer jargon, sort of like the recent NFA Handbook(they're working on another manual on procedures) and I don't believe this covers demils, one area that desperately needs attention.
With any luck LR will chime in soon and offer his "old school" wisdom, we've spoken about this very subject.