What is it? Some kind of plumbing part?

[grey95chevyboy]

Found this today in a spot I thought was a old site..unfortunately not so much. Looks old google search brings up a old lawsuit in 1915 between someone concerning the 170 cal design .

 

[Plug N Play]

https://www.sprinklerwarehouse.com/Aqualine-Brass-Gravity-Sprinkler-p/bhr.htm