[767Jockey]

Thanks, guys, but after looking at the pem nut on McMaster, it's definitely not what's there now. This thing looks like it starts as a smooth barrel with the inside drilled and threaded. It's inserted in the hole from the front, and sits flush with the front of the surface it's being inserted into. Somehow, a tool is used to compress the barrel so that a ridge builds up on the reverse side of the surface it's been inserted into, which keeps it from pulling through the surface when it's tightened up or subjected to load. I presume the small area where the barrel is actually passed through the metal surface it's inserted into swells against the wall of the hole it's mounted through to hold it in place. I checked the nut with a magnet and it's definitely steel. Anyone have any ideas here? I know this description is probably confusing, but I can't think of a clearer way to describe it.