Haven't fired it (with the 16 inch barrel) yet, but plan to get some range time soon.
Everything but the butt printed in gst3d PLA+, the butt is some no-name brand TPU.
Its a shame about gst3d no longer shipping filament, gonna make it difficult to color match if/when a part breaks.
UZI barrels are about 1/4mm larger in diameter than "stock" barrel. You only need to modify the inter diameter of the screw collar and everything fits perfectly.