Sterling SMG NERF mounting ring

This is a bayonet mounting ring for a NERF blaster. It has "texturing" that is based on the barrel of a WWII British Sterling SMG.

I've been designing a number of NERF barrel accessories. This is for a test print to make sure certain dimensional changes didn't break the fit.

They did break the fit: I needed to sand down the inner tube that inserts into the NERF barrel.
DO NOT FORCE or you may break your NERF blaster.

I would love to get feedback from people on whether this print and