Threaded 12 Gauge Shell

I loved DeSteiner's 1887 shotgun. Printed two sets of them, however looking at the remixes for the shell they either need gluing, or filament swapping which is fine until you drop the shell and it breaks. The glue didnt work for me especially when using silk filaments for the bronze part as the continuous loading/unloading of the shell destroys the bottom lip of the primer. Then you're just wasting the top part. My solution? THREAD IT. I remodeled the shell itself, and added threads to the base and top. By doing this, you can easily swap the top part to other color shell (black/red/blue/green) according to your liking and if the primer is damaged, you can just print the base and swap it out. The .3mf file is optimized for Bambu's X1C @ 0.16mm layer height, I have also added modifiers to the thread to increase its strength if dropped. STEP files also provided. Thread used is M10x1.5.I have tested the design extensively and so far the only part that fails is the primer lip fr