Just bought a three pack of P229 recoil springs, U.S. made, part # RSS-2299. Noticed they are solid wire not the braid type I'm used to seeing. Also they are longer stiffer then the braided type. Did sig change to a solid wire recoil spring ?

Current production guns have both

It seems like a remember 3 different types posted in pictures here. Braided, single, and flat. I don't remember the last time I saw one posted with a flat one, as I thought those were more common in the SIGPro, but the single pops up from time to time.

As a picky point about terminology, there are no “braided” SIG recoil springs. I won’t try to post a picture of braids here (search for “hair braids”), but braids are formed by folding multiple strands (commonly three) over and around each other. The multistrand SIG recoil springs are formed by twisting the wires around a central wire or axis.

No braids here (357/40 P229 spring):

I was just on the phone with Sig CS regarding my spring problem. The fellow said that 9mm now come with single wire springs, while 40/357 still have multistrand wire springs.

Given that some have noted that production appears to have both versions, I wonder if the assemblers of P229 are grabbing springs as if they are the same? The recoil spring weight is of course different for these two caliber families.

One might ask "why multistrand?" The answer is contained in this webpage, neatly summarizing my engineering textbook.

https://www.thespringstore.com...ng-fatigue-life.html

The goal of long life would require a good ratio of wire diameter to coil diameter, and short pitch. Given that the required pitch is also defined by the deflection distance, here the slide reciprocating distance, it would seem that a multistrand spring is optimum. Grouping several multistrand springs each having long fatigue life brings the total force generated up to the desired value.