Here is what Wolff has to say about springs inther Q&A section.
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4. How often should I change my springs?
The performance of your gun is the best indicator of when a spring needs to be replaced. Factors such as increased ejection distance, improper ejection and/or breeching, lighter hammer indents on primers, misfires, poor cartridge feeding from magazines, frequent jams, stove pipes and other malfunctions are all possible indications of fatigued springs or improper springs.
Springs such as magazine springs, striker springs and recoil springs are subjected to higher stress levels and will require more frequent replacement than other lower stressed springs such as firing pin springs and hammer springs.
Wolff springs are made with the highest grade materials and workmanship. Most Wolff [recoil] springs will remain stable for many thousands of rounds. Some recoil springs in compact pistols, especially where dual springs are used or are replaced by a single spring may require changing after 500 - 1500 rounds. Springs that become rusty, bent or otherwise damaged should always be replaced. Again, changes you observe in your firearm's performance are the best indicators that a change is needed.
5. How often should I change magazine spring? Should I unload my magazines, rotate magazines, load with fewer than the maximum rounds?
Magazine springs in semi-auto pistols are one of the most critical springs and are the subject of much debate and concern. Magazines which are kept fully loaded for long periods of time, such as in law enforcement and personal/home defense applications, will generally be subject to more fatigue than the weekend shooter's magazine springs in which the magazines are loaded up only when shooting.
Magazine design and capacity also affect the longevity of the spring. In many older pistol designs, maximum capacity was not the always the goal such as with the 7 round 1911 Colt magazines will last for years fully loaded. There was room for more spring material in these guns which reduces overall stress and increases the usable life of the spring.
More recently higher capacity magazine have become popular. These are designed to hold more rounds with less spring material often in the same space. This puts more stress on the spring and will cause it to fatigue at a faster rate. Unloading these magazines a round or two will help the life of the spring. Rotating fully loaded magazines will also help the problem somewhat but it is not always practical.
In applications where the magazine must be kept loaded at all times, a high quality magazine spring such as Wolff extra power magazine springs, will provide maximum life. Regular replacement of magazine springs will provide the best defense against failure from weak magazine springs. Regular shooting of the pistol is the best way to be sure the springs are still functioning reliably.
6. My spring got shorter after I used it for a short time. Is it bad?
Most new springs will take a set when they are first compressed. That means they will shorten up. This is a normal event and you should not be immediately alarmed. The greater the stress on the spring, generally the more set that will occur. All Wolff springs take this set into consideration. The ratings of the springs you receive are the ratings after the set has occurred. After set has taken place, the spring should remain essentially stable for the life of the spring.