I’m looking for any information on the middle shell in these pictures. It’s flanked by a 9mm rimfire and an Eley 360 for comparison. I have it listed as “9mm centerfire shotshell” but don’t really know anything about it. Years and years ago when I first started collecting, I was approached by a stranger at a flea market where I regularly dug through boxes of loose ammo. “You that kid that collects cartridges?” I said yes, he fished this out of his shirt pocket, handed it to me, and walked away. Dimensions are as follows.
Rim: .444" / 11.27mm
Head: .387" / 9.83mm
Tube: .378" / 9.60mm
Length: 1.575" / 40.00mm
Despite the picture, it’s more red than orange.
Any and all information is appreciated.