It’s hard to believe that anyone could improve on something the Swiss built but we did! Introducing the RSI custom wound Swiss K-31 Firing Pin Spring. This spring was developed in a joint venture between the owner of WWW.SOCAMO.COM and C&R Spring Company LLC, the same guys who designed our incredibly popular Mosin Nagant spring. Their goal was to create a spring that would improve the functionality of the Swiss K-31 rifle without sacrificing reliability. Each spring is made using high quality steel, the spring ends are then squared and ground. Then they are treated with a black oxide coating to prevent corrosion. Once the spring takes a “set” in the bolt the user will see a noticeable improvement in the performance of their rifle. The new design significantly decreases lock time and to improves bolt cycling (one of the biggest complaints about the K-31). This new spring also makes it easier to disassemble the K-31 bolt for cleaning.