Last year I sent my .40 P226 to SIG for their "SIG Service Package" to replace old night sights, small parts, inspect, etc. The gun was returned with a new recoil spring (top) as part of the package:
Old used spring is bottom. The new spring is slightly shorter than my used spring, is blue, and has different coiling. My previous springs were green as I recall. Did SIG send me a P229 .40 spring instead of a P226 spring? I only now noticed this because I continued to use the old spring for a while and this isn't a gun I shoot often. I emailed the rep who facilitated this service but figured checking here couldn't hurt.