Here's a guess, but it is based on the items "looks". The shape/design and material looks very much like the barrel taps from the 18th and 19th century. I'm not aware that this was ever a normal procedure, but this item looks like it could be tapped into the hole of the barrel to "shut it off" a little more securely than the tap itself. The knurled rings and the end knob would make removal easier when it came time to remove. You requested "ideas", so this is just another to consider.