This kit contains one (1) ISMI Chrome Silicon Spring and one (1) Magpul Gen 2 follower. These parts replace all moving items in a single USGI 30 round magazine. Add a Ranger or L-Plate at a discount with the kit.

ISMI Spring information:

General Information: "The alloy spring steels have a definite place in the field of spring materials, particularly for conditions involving high stress and for applications where shock or impact loading occurs. Alloy spring steels also can withstand higher and lower temperatures than the high-carbon steels and are obtainable in either the annealed or pre tempered conditions". This covers Chrome-Vanadium springs as well.

Corrosion Resistance: Similar to 17-4 stainless.

Post-Treatment: ISMI springs are heat-treated and stress-relieved to improve performance. Not all CS springs are treated after winding which degrades performance.

Operating Temperature : Music wire springs have a surprisingly deficient low operating temperature of 0 deg and a low maximum operating temperature of 250 deg. The minimum temperature is difficult to find and is unverified at this time but the maximum is verified. As stated above in the general information, CS has a better temp range. Minimum is unknown but maximum is 475 deg F.