This spring is designed to fit the stainless steel guide rod in the MR/DR/XR pistols.
Shadow Systems’ Springs are formed from high-quality chrome silicon material. There is some debate on this point, but we do feel that chrome silicon springs are simply a higher quality, longer wearing spring, ESPECIALLY in high heat from extended firing. We typically recommend changing springs at around 5,000 rounds, but we have run these springs for as many as 10,000 rounds.
Standard Factory Weight: 18 lbs. spring. This is what ships from the factory.
Lightweight: 15 lbs. spring. Used in cases where light ammo or muzzle devices are causing short stroking (failure to extract/eject typically).
Heavy: 20 lbs. spring. For use with very heavy ammo or suppressors that are not allowing breech to fully close. Typically, this is the spring for suppressor reliability issues.
Fits Shadow Systems stainless steel MR/DR/XR guide rods
Restrictions: By buying this item from Shadow Systems, the Customer certifies that the Customer will comply with any and all requirements imposed by applicable U.S. federal, state, and local laws, regulations, and administrative policies.