About this 3D model

This is the muzzle tip from a WWII British Sterling sub-machine gun. The diameters have been scaled, but it appears surprisingly accurate. Yes, the cylinders are supposed to be off center. :-) I've been designing a number of NERF barrel accessories, and the diameters on this model have been scaled so that a regular NERF dart will fit through the middle, and so that the outer diameter matches a cylinder that fits the outer diameter of certain NERF blaster barrels. This model is for a test print to see how a finished piece will look. I'm unhappy with the 2 prints I made, but the problems are slicer/printer configurations.