Found at a park dating back to the 1890s. Previously farmland. The park had dance halls, theater, and had military exhibitions in about 1910 (we find a ton of blanks, bullets and shell casings). The park had civil war camps, gypsy camps, trolley line and amusements. Fishing lake and a pool too. And golf nearby. This park has been everything. And now just sad and decrepit.
Thanks DC and ticndig but the hole is so tiny that I can't see it used for those purposes. I could barely get a stripped twist tie wire through it. But I don't know why it's hollow or if firing parts are hollow.