Colonel Wasp Firefly Shell

I designed a Colonel Wasp Firefly shell that is getting the same velocity (200ish FPS) as the molded shells. This also has the ability to rear load the dart. I have found it best to push the dart about 1/4 of an inch or 6ish mm from the bottom of the shell for best consistency and velocity. I print at 100% infill with no supports or brim at 0.2.