note: i edited the shell eject hole location in the first pic (current picture isn't updated)
Make a full set of 'moddable' gun models like a modular gun with switchable parts in (choose a different stock/sight/body+barrel length/magazine/whatever else), and icons for each toggleable part, and then we could make a GUI and a full mod of it <3
(by using a single item and a set of images for it, and then projectiles switchable by the type of mag you insert and spawned dynamically via script instead of just defined)
You could even make a pistol/SMG one and a separate rifle one for a fullsize rifle.