Spring upgrade,no chrono surprises.
Plug in your current spring, real chrono reading and target spring. The calculator preserves your gearbox's actual efficiency and shows what to expect — velocity, FPS and joules.
Ratio between your real chrono reading and the spring's theoretical value. 100% = ideal setup.
/ How it works
The math, in plain English
Efficiency carries over
If your M100 reads 95 m/s instead of the theoretical 100, your gearbox is running at 95% efficiency. Swap the spring while keeping cylinder, barrel and seal — efficiency stays roughly the same.
Typical efficiency
Decent stock: 90–95% · Well tuned: 95–100% · Below 85% you have an air leak; check seal and cylinder before upgrading.
When math isn't enough
Big jumps (M90 → M150) often need a wider cylinder, full metal teeth piston, reinforced air nozzle, higher-torque motor. The calc gives expected velocity — not the mechanical health of your gearbox.
Theoretical estimate. Real-world variables: air seal, cylinder length, barrel volume, hop-up, temperature, wear. Always re-chrono after the upgrade.