AEG Spring Upgrade: Choose and Test Safely

An AEG spring affects the load placed on the complete drive train. Choose it around the field limit and the condition of the gearbox, not from an assumed FPS number printed beside a spring rating.

Check the build first

• Confirm the field’s energy or velocity limit and required BB weight.
• Inspect piston teeth, gears, bushings or bearings, spring guide and gearbox shell.
• Consider motor, battery, wiring and ETU load.
• Correct air leaks before choosing a stronger spring to compensate for low output.

Spring labels are not a finished result

Output varies with the spring, cylinder assembly, barrel, seal, preload and measurement conditions. Treat any nominal spring rating as a selection reference, then measure the completed replica with a chronograph.

Test after assembly

Start with controlled semi-auto cycles. Stop if the gearbox strains, stalls, overheats or sounds abnormal. Check motor and battery temperature, then chronograph the same BB weight used for the field limit. Reconfirm compliance after the spring settles.

When changing spring load together with gears, review the airsoft gear ratio guide and assess the complete drive train.