S&W M&P 9mm~40 questions


February 26, 2012, 03:31 PM
I have been eyeballing a new compact pistol for a while. The other day I happened to pick up a S&W M&P in 357 Sig.
I really like the way it fits my hand, which is a big deal because a lot of Hi cap guns are just too big for my hands.
I really know nothing about these pistols, what are the good and bad aspects?
Also wondering if, like some of the other pistols out there, you can change calibers with a barrel swap?
Will the standard barrel work in the compact model?

Just curious what those who own or shoot them think and know?


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The Lone Haranguer
February 26, 2012, 04:02 PM
I had a 9mm compact that functioned 100% perfectly, from the very first round. The only criticism I had of it was the width of the slide. It was a little less comfortable to carry IWB than a slimmer gun. Prior to that, I had shot a 9mm full-size as a rental. Its performance is what inspired me to buy it.

February 26, 2012, 07:54 PM
Yes, the M&P's do have conversion barrels available, but all that I have seen are .40 S&W -> 9mm. Nothing for .40->.357 or .357->9mm

I love my FS M&P9. Some people don't like the stock triggers, but I don't mind it. If you don't like the stock trigger, APEX Tactical Solutions has several aftermarket parts to solve the problem.

February 26, 2012, 10:41 PM
40 & .357 Sig are interchangeable. 9mm covversion barrels will fit in either a .40, or .357 Sig, but, if you buy one in 9mm, that's the only caliber you can use.

February 27, 2012, 12:13 AM
The information posted seems a little confusing. Hope this clears it up a little.

ANY 40 S&W pistol can be converted into a 357 Sig, with a conversion barrel. Both the 40 S&W and the 357 Sig use a 40 S&W case (almost) the 357 Sig case is just a tad longer. But the slide, extractor and mags will work with both so they are inter-changeable. 9mm pistols are generally not convertable due to mag well size and bolt face on the slide. Some 40 S&W pistols can use the 9mm conversion barrel since the chamber will support the case and not the slide and extractor, however the mags need to be changed to 9mm mags since the 40/357 mags will not feed the 9mm case.

However, be warned that the max pressure for a 40 S&W round is about 35,000 psi and the max pressure for a 357 Sig is 38,000 psi, so check to see if your pistol is rated for the 38,000 psi before converting it to 357 Sig.

Like I said, I hope this clears it up a little.

February 27, 2012, 10:16 AM
As stated above all that is necessary to switch from .40 S&W to .357 Sig in the M&P line is a barrel change. Not a conversion barrel just the standard S&W barrel. I've done it on my M&P full size.

If you plan on doing this it seems that the .40 barrels are easier to find than the .357 barrels for whatever reason. (at least it was when I was looking anyway)

February 27, 2012, 12:51 PM
The one I am looking at is a 357 Sig
So I would suppose I would be good to go either way?

February 27, 2012, 01:45 PM
Yes, you're better off buying the .357 sig pistol then picking up a .40 barrel as the .40 barrels were easier to find when I was looking. Magazines are the same.

They're great pistols, I have both the compact and fullsize versions and love them.

February 27, 2012, 08:37 PM
I love my M&P 9c....my only regret is I didn't buy a 40 so I could do the conversion. I'm giving the M&P 40 full size serious consideration for my next pistol.

February 27, 2012, 10:29 PM
read my post on the new trigger for m&p that will be out for summer

February 28, 2012, 12:39 AM
I actually read some of it already. Is this trigger option available on the new M&P?
can it be retrofit to older models?

February 28, 2012, 11:30 PM
I prefer the trigger pull of the M&P over any stock Glock I've fired. Mine is extremely smooth and the reset was fine for the first 8000 rounds. I did install a heavier return spring after that and a RAM and I think its perfect now.

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