New challenge!!!! shell casing type???

Ok folks, I have a challenge for you. What is this shell casing? A Friend of mine gave them to me. He got them (about 150) from his grandfather

Game Boy Pocket Replacement Shell, RetroSix

Shop for Fortune Cats PC products at the PC & Video Games store.

Replacement Hard Back Bottom Housing Shell Case Cover Back Faceplate for Nintendo Switch NS Console Cover Plate - New Edition (C)

Zelda Gold Color Replacement Case Cartridge Shell for N64/ SNES/ NES majoras Mask Style

ICv2: Help Turtles Find Love in 'Shell Company: Don't Write Me Off

How to Read a Box of Shotshells

Hard Host Protection Sleeve PC Game Console Accessories New

Fiocchi Adds New Knock Down Big Game Cartridge Series. Here' - RifleShooter

New Plastic Game Housing Case Cover For Gameboy Color Console GBC Shell With Buttons Kit Sticker Label FREE SHIP From Gamingarea, $4.19

3 Shell Game - Jack Chanin Hello Sucker Booklet, 3 Shell Monte

Classic Limited Edition Replacement Case Theme Style Shell With Buttons For Handheld GBA SP Shell Case SP Game Console From Botuo68, $7.32

New Style Multifunction Case Hard Shell Travel Carrying Protective Storage Bag for Nintendo Switch Red/Blue/Gray/Black