You have no idea, bro. No idea. I built a fucking gun because I had a spare gas tube roll pin...
It's documented somewhere here, when it all went down. It was fucking stupid, and there's an OLD thread on it.
I cured myself of that bullshiit, though, and bought a dozen gas tube roll pins - just to prove it to myself.
A few years ago, some anonymous bastard shipped me a bulk order of MagPul aluminum trigger guards. I didn't know where they came from, they just fucking showed up on my PO Box. - Out of nowhere. Nobody ever admitted to it. Those fuckers spawned some rifles, all on their own.
"Sickness" doesn't even scratch the surface, especially when people are ambushing you with parts, that you had no idea about... It's assinine...