My OEM/factory .357 SIG barrel was delivered to another address. I told my cousin about this and he stated that the factory S&W .357 SIG barrel WILL NOT work in the FS M&P .40. I had read on here somewhere, and other forums, that it would work. That's why I ordered one.
Can anyone out there that has this barrel in their M&P .40 clarify this for me? THANK YOU!

i have a factory .357 sig barrel I ordered a while back for my full size M&P 40 - works fine, not sure if they have made any changes since I got it several years ago

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Steve

It will work just fine. I have both the fullsize 40, and the 357 sig. I have swapped the barrels between both, and have fired them without issues.

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The Penetration Channel

That's what I get for listening to family, a panic attack.
Now I have to wait on MIDWAY to send me another barrel.

Mine probably doesn't know that it not supposed to work - Works like a charm

I bought a SIG.357 and 9mm to .40 conversion barrel for mine from FleaBay.
D1, how did you get a vacation?

I got one in my FS40 and it has run flawlessly since the install. I've had no issues with it whatsoever and I've shot it a lot.

Mine works flawlessly.