m&p recoil assembly, 9mm vs .357sig

[CaptainPlanet]

Hey guys, just had a question regarding the 4.25 inch m&p's recoil assembly. According to Jeff (sw cs) and wolff the 9mm, 40, and .357sig m&p's use the same spring. I also looked at a parts list on sw's website and the same number is used for all three calibers.
My 9mm m&p has a blue spring while my recently purchased m&p .357 has a green spring. I know that color means nothing however the spring in the .357 is much more stout and has about 5 more coils then the blue spring in my 9mm.
I purchased my 9mm in January 2010 and picked up the .357 about two weeks ago. Just wondering if anyone else has noticed the difference and could clear up the confusion I have since it definitely appears that both springs are NOT the same weight. Also, my 9mm spring is not near the change interval, she's only had about 550 rounds downrange. Thanks

[handgunner356]

There is a possibility that they have a different supplier for the recoil spring. The 40/357 uses a heavier slide than the 9mm so it can use the same spring.

[CaptainPlanet]

Originally Posted by handgunner356

There is a possibility that they have a different supplier for the recoil spring. The 40/357 uses a heavier slide than the 9mm so it can use the same spring.

Thanks gunner. One last thing, is the factory weight 16 or 18 albs? Smith is claiming 18 while wolff and ismi say its 16. Appreciate the help

[handgunner356]

Well that too can be deceptive, depending on how each manufacture rates their springs. Usually under a certain compressed length for a perticular gun. I like to watch my ejected brass and look for it to go 3-6' or so. If I find it going much over that I'll install a heavier spring. If it barely falls out of the gun or the slide doesn't lock back when empty I go with a lighter one. Most likey whatever the manufactor recommends for a certain gun will work for most loads, you usually run into problems when you use hotter or lighter loads-for-caliber than the standard rounds.

[CaptainPlanet]

I'm sure a pound or two won't make much of a difference since all M&p's aren't finicky. (or at least none of the ones I've shot) Just a little "Carry Gun ocd I guess" Thanks again Gunner

[WR Moore]

Could be a production change, or as noted, just a different supplier.

[pyper22]

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Originally Posted by CaptainPlanet

Hey guys, just had a question regarding the 4.25 inch m&p's recoil assembly. According to Jeff (sw cs) and wolff the 9mm, 40, and .357sig m&p's use the same spring. I also looked at a parts list on sw's website and the same number is used for all three calibers.
My 9mm m&p has a blue spring while my recently purchased m&p .357 has a green spring. I know that color means nothing however the spring in the .357 is much more stout and has about 5 more coils then the blue spring in my 9mm.
I purchased my 9mm in January 2010 and picked up the .357 about two weeks ago. Just wondering if anyone else has noticed the difference and could clear up the confusion I have since it definitely appears that both springs are NOT the same weight. Also, my 9mm spring is not near the change interval, she's only had about 550 rounds downrange. Thanks

i would think color would I.D. the spring weight, it does in glock's. my 357/40 is green. a 9mm has a lighter bbl. and slide so it could use a lighter spring. pyper22

[WR Moore]

S&W notes that color on springs DOES NOT have anything to do with spring tension. All the 9/.40/357 recoil spring assemblies have the same part number.

[41 Mag-Man]

I've had the same issue my M&P40 has a blue spring and the
M&P357 has a green. I'm not the brightest bulb out there but I feel a difference. I used a home made spring gauge to see how much, granted my way of testing is hardly scientific, but there is a difference. Just to add a little more confusion, I shoot a Storm Lake 9mm conversion barrel in both M&P's, no changes of any kind just drop-in, change mags, blast away, both work with no hiccups.

[kend]

My connection at S&W has assured me the guide rod assemblies are the same. The different colors have nothing to do with specs, they simply designate which supplier they came from. It's for use inside the factory and, again, has nothing to do with specs. The 9, 40 and 357 use the same guide rod assembly.