I know all about the rules of thumb and the manufacturers recommendations. What I'd like to know is if there is some way of objectively measuring the spring to determine that it needs to be replaced. A new spring is going to take a set very soon after it is installed, so maybe the trick is to measure the length a new spring after 100 rounds and then look for additional set? Maybe you could measure the force the spring exerts and look for a change?
Since other folks like to resurrect threads, thought I would as well. This was the oldest thread I could find in the 1911 area and it was never answered. The manufacturers guidelines are just that - guidelines. Symptoms of a weakening recoil spring are: The slide not returning to battery as it should Cases being ejected much further than normal Significant change in "feel" while shooting The bottom line is that recoil springs are cheap and should be changed whenever it appears the "behavior" of your gun has changed...
Another way is to compare the length to a new spring of the same poundage. If it is one inch or more shorter than a new spring, replace it.
I decide to swap out the recoil spring on my Kimber and the new one was 1" longer than the factory installed spring.
Due to the different steels used and the different configurations (flat vs braided, etc), I never put a lot of stock in spring length...
That's why I always measure a new spring when I install it the first time. From the ISMI site; "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)." * 22.7% ISMI Gunsprings, Made in the U.S.A. Dave put it best, When the premium replacement part is $8 why are you even asking the question? If in doubt, change the damn thing! If you are not using ISMI springs in your autoloader you have either spent the last five years in a coma or you're just stuck on stupid! Its the only recoil spring with a one year TOTAL warranty. Again, from the ISMI site; "12 Month Replacement Warranty extends beyond just materials and workmanship. We even cover failure due to wear." Do yourself a favor and go to the site and read. Still not convinced? Dial (765)565-6108 and ask for Marc Cosat and let him tell you why you should be running ISMI, “The World’s Finest Gun Springs” in your gun.
