What is the difference between a chrome silicon spring from, say, Brownells and the ISMI chrome silicon spring, other than price? MagPul is now offering them as part of an attractively priced rebuild package.  Attractive ONLY if the ISMI springs are superior. Does anyone use a chrome silicon buffer spring? BTW, my research indicates that Wolff springs are neither; they are supposedly case hardened steel.  Anyone know about SAW red springs?

All the chrome silicon springs out there are probably better than standard springs.

We sell ISMI springs because one of our engineers thinks it is the best 30 round mag spring on the market, however they also cost more than other chrome silicon springs so you will have to judge for yourselfs if they are worth the extra cost over other options.

Our ISMI buffer spring and mil spec buffer set is chrome silicon.

Here is some information I was sent concerning ISMI springs (some of it relates to all chrome silicon springs too)

General Information (Acxess Spring): "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 (Marc Cosat): Similar to 17-4 stainless.  He has anecdotally related that there are water born units that use these springs and have not related any corrosion issues to him.  This tells me that the practical level of corrosion resistance is NO WORSE than music wire.

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

Operating Temperature (Marc Cosat and Acxcess Spring):  Music wire springs have a surprisingly deficient low operating temperature of 0 deg (Fahrenheit) 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.