Stupid Airsoft checks the spring cylinder upgrade for the Action Army AAC-C1, a airsoft sniper rifle capable of running on gas, CO2, or spring power. He begins by detailing the internal components of the VSR-spec spring kit, highlighting the metal spring guide and a unique piston design that utilizes O-rings instead of a traditional piston cup. He notes that while O-rings may wear faster, they are significantly easier and cheaper to replace than proprietary piston cups found in other high-end models.

The installation process involves disassembling the rifle's upper and lower receivers to swap out the existing gas cylinder for the new spring unit. The host walk viewers through the necessary modifications, such as removing the chambered round indicator bar to ensure the new cylinder fits properly and swapping the bolt handle over to the new assembly. Stupid Airsoft emphasizes that the upgrade is relatively foolproof and straightforward, even for those with limited technical experience, as long as the different screw sizes are kept organized.

Performance testing reveals that the spring conversion offers superior consistency compared to gas or CO2, as it eliminates variables like temperature changes and pressure drops. Using .43g BBs, the rifle produced a steady output of approximately 1.5 Joules with a very quiet muzzle report and a smooth bolt pull. In the end, he says that the spring upgrade is a highly effective modification for players seeking a reliable, low-maintenance sniper platform that performs predictably in various weather conditions.