S&W M&P .40SW to .357SIG conversion.

[icebones]

Can you convert a factory stock M&P chambered in .40 to .357 SIG by buying an aftermarket barrel? Or does the recoil spring need to be changed also?

 

[Black Butte]

Yes, you can convert your factory .40 S&W M&P to fire .357 Sig by simply swapping out the barrel. You shouldn't have to change the recoil spring to have functionality, but some like to "tune" their pistol by choosing a spring from Wolff that gives them the best results. Such a spring may deviate a few pounds from the factory-weight spring depending on:

(1) the grain weight of the bullets being fired,
(2) how hot the cartridges are loaded, and
(3) the rigidity of your grip on the pistol.

 

[jdh]

Point of impact is about 2" different at 15 yards. Other than that there are no issues with just a barrel change.

 

[ElrodCod]

The 9mm, .40 S&W, and .357SIG all use the same recoil rod assembly. All you need for conversion is the barrel.