Check this customised Tokyo Marui M4 SOPMOD NGRS that was turned into an M16A1 XM16 NGRS by Nextgen Retros. This uses a custom E&C Upper, custom G&P AEG front set, and a custom AEG stock. The next plan is the installing an A1 correct as well as a period corect A1 G&P stock.
We hope that the Tokyo Marui product designers are watching this and may want to design retro NGRS airsoft rifles such as the XM16, M733, and more.