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Riptide Rails Enhanced FGC-9 Bufferless Bolt
(forum.guncadindex.com)
Also 2 benefits to the GF is the ability to dye it and the price point.
You could try the Prof parabellum Hybrid Square Tube SMG under “hybrid designs” on the Gatalog
You could also mill triggers and whatnot. If you got a CNC you kinda need to carve your own path here. Start with small stuff and work up.