don't think there's a step
I know how you came to this idea, taking a closer look at the underside of the stylus brush section...but it seems to be just the way the light/ shadow is interacting with the prominent knurling. If you look at the upside, better lit area of the brush, there is no visible step. so why should it be present on the opposite side?
the MG81 flash hider with the "fake" funnel section is obviously resin.
see the color difference between the aluminum parts at the side at the amber areas at the knurling of the fh, where the paint has worn off. plus, the backside where the ruger barrel inserts is solid vs. hollow
Markus