Mach Sakai takes a long gas blowback rifle for a review in this video, the Mach Sakai: FN M16A4 RIS GBB from S&T. This has a polymer receiver with a 485mm outer barrel with a 45mm flash suppressor. It has the carry handle and polymer fixed stock as well as a 317mm RIS Handguard with 4 rail covers. He tests this GBB for operations, externals, and performance in a steel challenge.