Captain Airsoft's video shows the process of modifying a WE L85 Gas Blowback Rifle (GBBR), a replica of the British Armed Forces' standard-issue bullpup. The project began with an evaluation of the rifle's performance in its stock configuration during a team deathmatch event. Initial field tests revealed technical issues, specifically mechanical jams when firing in semi-automatic mode, which the creator temporarily addressed by adjusting the nozzle guide screws and applying lubrication in the field.

Following the initial trial, the rifle underwent a series of internal upgrades to improve its consistency and range. The modifications included the installation of a 510 mm Maple Leaf Crazy Jet inner barrel, a Quad hop-up rubber, and an RA Tech magnetic locking NPAS (Negative Pressure Adjustment System). These components were selected to resolve the previous semi-auto firing issues and to increase the rifle's effective range, with the goal of achieving reliable hits on targets beyond 70 meters.

The final segment of the video showcased the upgraded L85 in a gameplay session at Driverwood Airsoft. During the second field test, the creator reported a noticeable improvement in accuracy and muzzle velocity, comparing the modified bullpup's performance to that of a designated marksman rifle. Despite continued minor issues with magazine gas efficiency, Captain Airsoft that the internal upgrades successfully transformed the replica's performance capabilities for competitive use.