Complete Tuning Kit

Complete Tuning Kit

Five springs. Every weight. One box.

Stop guessing which weight your build calls for. The Complete Tuning Kit puts the full VPRS-15 range and both MilSpec sets on your bench, so you can test them back to back and keep what feels right.

What's in the kit

Variable pitch, not linear

The VPRS-15 is wound with variable pitch. Coil spacing changes along the length of the spring, so tension builds progressively through the stroke instead of staying flat. Install with the closest coils at the rear.

MilSpec sets

Precision-engineered spring systems designed to refine standard mil-spec setups without replacing the whole assembly.

These aren't reduced-power, just-for-fun springs. They're calibrated spring rate systems developed for a consistent feel and a clean return, while keeping everything mechanically sound.

Most factory mil-spec setups ship with heavy return springs sized for universal reliability, which leaves more weight and more stacking than most builds need. These sets replace them with calibrated rates and keep your existing components.

Before you run it

Lighter spring weights change how your setup behaves. Test thoroughly after install, and if you aren't comfortable swapping springs yourself, have a qualified professional handle it.

Why Neptune Defense

70 years of spring manufacturing experience. Lifetime warranty on manufacturing defects.