Recoil Spring Length
Howdy sm,
Recoil spring free length may vary from spring to spring within the same lot.
After installation and use, the spring generally takes a set, and the rate is
figured in after the set...so a new spring may actually test out at a different
load than one that's had 50-100 rounds go down the tube.
Generally speaking, Wolff springs are about optimum free-length with 32
coils, regardless of the rating...and the check to determine the correct length for the gun isn't in the free or pre-load length, but rather the
compressed length with the slide fully rearward. As long as the spring
doesn't go into coil bind....stacked solid...the spring is okay. Also generally
speaking, the more coils the better. Sometimes, a spring needs to have a
half coil or so clipped for best function, but that's a rare case. Other times,
a spring needs to be clipped to prevent bind, but it's usually on pistols
with Commander and shorter-length slides.
ISMI springs come out of package overlength, and need to be fitted to
the gun.
As for checking to see when a spring is "worn out", the rule of thumb is
to lay it beside a new spring of the same rate and compare the free lengths. If the used spring has lost 2 coils in length, it's time to change.
Some need a change at 2,000 or so rounds...some seem to go on almost forever. Shorter springs....such as in Commander-length pistols, require
change more frequently than full-length springs.
On Gary's malfunction...my best WAG is that the magazine springs have
gotten tired. The feeding round isn't getting that last, little bit of upward
push needed to get the rim under the extractor...and if this is it, the malfunctions will become more frequent with use. ANY 8-round, flush-fit
magazine necessarily has a mag spring with fewer coils. They're already
on the edge, and it doesn't take as much use to weaken'em to the point
of causing problems.
Cheers!
Tuner