So, I looked up their web site:

cerrofabricated.com: Forged Defense Components

I'm going to take a stab that a small slice of their alloy casting business is devoted to AR-15 items. While I didn't dig far into the matter, the castings are probably OEM items utilized by one or more company which uses them as part of the assembly of assault rifles.

Long story, but back in the early 2000's I ended up with two manual Bridgeport vertical milling machines - old, but in perfect condition. I decided to convert one to a CNC tool (as a hobby project) and sold the other one on E-Bay to finance the project. It was bought by Armalite (the manufacture of the M16). I was curious and asked why they had bought what amounted to an antique tool (I think it dated to the early 1960's). They said that they used them to create a thread for the flash suppressor. While Bridgeport was already out of business, even their "legacy" tools were vasty superior to contemporary Chinese "clones".

So, the question is whether that sale makes me complicit in whatever those rifles were used for?

Jeff