I'm sure I have read something about the device actually acting on the clip, as opposed to just being a guide slot and no more.

While the inletting does not appear to have been done in one pass of the cutter, it is certainly nice work! For that matter, I'd guess that the real ones are custom inletted as well - doubt that they would change the tooling setup for a couple of hundred pieces.

A similar case occurs with the 26" BoOF stocks, but simpler, all they had to do (in addition to NOT doing something) was crank the clamp over 4", with no cutter change-out required. The increased taper was likely done by just a little longer stint on the belt sander.

I don't know where this recent find fits into the chain of events, but IMHO it should be treated very kindly, and nothing done to it in a rush. Sort of a treasure, really - could (even if a lunchbox special) wind up being quite valuable. Of course, if it could be some sort of intermediate prototype between 4070 and the production guns, it could be almost priceless.