For a 5" 1911, manufacturers often say
How often should the recoil spring be changed? The recoil spring should be changed, at the latest, when it has lost 0.500” of free length from new. At this point, the spring has suffered a considerable reduction in load exerted at installed (when the gun is in battery).
For the flat wound springs like the full size M&P, this method does not work, and fatigue testing on the flat wound springs gives incredible results:
How long will an ISMI recoil spring last? In independent testing, ISMI spring have endured in excess of 100,000 compression cycles. We don’t recommend going that long between changes however. With an ISMI spring, practice routine maintenance and change it once a year.
Once a a year is reasonable for competitors, who may shoot many tens of thousands of rounds a year. ISMI guarantees their spring for one year, regardless of the number of rounds fired. I personally have fired over 20K in one year, and a friend fired 63K. Both recoil springs were still fine.
For the average shooter who shoots a few hundred shots a year, a RSA may last a lifetime.