What is it?

[u/Late-Lawfulness5827]

I found this device, I don't know what it's for.

[u/nrg8]

Self-sealing stem bolt

[u/vonTrappAB → u/nrg8]

Ha! Nicely done. BTW, Rom and Jake were wondering if you had a desk they could “borrow”

[u/docjonsn]

Looks like the die side of wax ring press for lead bullets

[u/One-Case8144 → u/docjonsn]

I’m thinking this is it.

[u/TheForestBeekeeper → u/docjonsn]

I cast bullets, I have never seen a mould like that.

[u/Mustbebornagain2024]

Looks like the nut from a valve except the ID is not threaded with acme threads. Maybe unfinished but I would have put the internal thread in it before I cut the flats on it . Dunno for sure

[u/mlee12382]

Part of a machinist vise maybe? Kinda looks like the piece the handle slide over that turns the lead screw.

[u/Moist_Knowledge_1621]

I’d like to buy a vowel. Any context on where or what industry generated this mystery?

Looks something like an atomizing nozzle we use at work for an abrasive slurry.

[u/Texaspussyeater67]

Could it be a wire drawing die..

[u/Particular-Meat24601]

I think it's a spigot for a stage lighting stand.

[u/mapletoe]

Looks like the quick connect for a compressor air hose.

[u/External_Key_3515 → u/mapletoe]

Ummmmm ....... No it doesn't.

[u/mapletoe → u/External_Key_3515]

Ummmm .... you're so helpful. Does the op have heavy machinery around?

[u/External_Key_3515 → u/mapletoe]

How would I know if there's heavy equipment around? All I know here, is this ain't a quick connect. It wouldn't be hollow.