The spring is the base of the airsoft gun. It is a part which notably affects shooting range.
This spring is made of tempered SiCr alloy steel wire, a material primary dedicated for machine springs under rhytmic load. Our spring was tested under real airsoft fire, and after 10000 shots had no lenght or output change.
Progressive (nonlinear) winding gives a lower resistance at the first phase of pressing, but the spring keeps the same power.
Suitable for SVD sniper rifles, and may require replacing the center ring.