I thought I'd add a comment from Marc Cosat at ISMI on gun springs.
"...ISMI premium springs are manufactured exclusively with certified aerospace specification alloys; stainless or chrome silicon. Then our springs are heat treated, shot peened and stress relieved after winding to enhance performance and durability. Our springs utilize the same design and manufacturing technology as used in IndyCar and Formula One racing. In a typical 500 mile race, a valve spring in an IndyCar will go through more than 2,500,000 compression cycles. Consideration of factors such as modulus, wire diameter, mean diameter, active coils, total deflection, spring relaxation, maximum service temperature, and operating environment; results in you having modern spring technology available for your pistol.
Because of the properties of music wire; it cannot be heat treated, shot peened and stress relieved after the spring is wound. Additionally, music wire lacks consistency from bulk lot to bulk lot. This results in inconsistent performance from spring to spring. This is the same technology that was in use 90 years ago when John Browning designed the 1911 style pistol.
We believe that springs shouldn’t be an ongoing worry or concern for the shooter. Springs should be an annual routine maintenance item. Change them once a year; go shoot and have fun..."