Nerf shell 9/16ths brass

A custom shell for my custom blaster. Figured I'd upload it even though the blasters not made yet... It was designed to fit 9/16ths for a reason, and that reason is my chosen barrel.
this means the brass part will slide over the barrel, making a seal between the "shell" and the barrel. I would just use the brass, but since this is going to be an HPA/LPA blaster, I need a good seal against the tank. Thanks for reading, please let me know your thoughts