Luca from Sabre Airsoft detailed the repair and upgrade of a Golden Eagle MG6588M M4 airsoft replica, a WA system-based model brought in by a customer experiencing complete gas blowback upon trigger pull. Diagnosing a missing rocket valve, Luca ingeniously replaced the stock nozzle with a modified VFC M4 V3 nozzle and enhanced the rifle's performance with a Quantum Magnus Pro hop-up unit. Further improvements included the integration of a GHK feed ramp and a distinctive real steel handguard from Unique AR, with Luca elucidating the nuances of the gas blowback mechanism and the impact of these modifications on the replica's overall functionality.