Model 1 receivers are FN.

Yep, no one has a FN idea who made them.

-- Chuck

When you say "make", you mean different things to different people.  The raw, solid aluminum forging blank will be made by a large aluminum company, and this is the die marking you may see on the upper.  The source of the forging, though, is the least important issue, because the same few people supply raw forgings to everyone.

Issues that ARE important:

- Was the part machined to spec?  If not, which steps were skipped?
- Was the part gauged to ensure that it ended up in-spec after the finish process?
- Was the part Hard-Coat Anodized?
- If not, what finish process was used?

Unfortunately, getting the answers to these questions is not easy.  Parts vendors like Model 1 buy parts from several different sources, so an upper you buy today may be supplied from a different source than what you would get tomorrow, or what you got last week.  And, uppers aren't usually marked by the manufacturer/machine shop that made them (again, the forge die marking doesn't mean anything).

That doesn't directly answer your question, because there is no one correct answer.

-Troy