I found this when I was looking through a very old box of bullets and at first, I thought it was a 4 gauge slug but the dimensions are too big (Nearly 1.5 inches at the band). Does anyone have a clue what it belongs to?
M203 40mm grenade launcher?
??? No clue. I did look closer at it and at two points near the tip on opposite sides it looks like rifling engaged it.Looking at it again, I think it's just some form of lead cap or plug for a pipe or container of some sort.