Another look at the AR15 NEPTUNE Sentinel 8" M-LOK AEG from Rossi of Brazil in this video review by GM Tactico. The Rossi AR15 Neptune Sentinel 8" M-LOK AEG 6mm is a metal and nylon airsoft rifle with a 100 BB mid-cap magazine. It shoots up to 380 fps and has a 6.03mm precision barrel, adjustable hop-up, retractable stock, and spring-loaded sights. It also has a metal reinforced piston and gear box.