Is this true?

[Helderberg]

I just added a M&P FS 9mm to my small family of Smith handguns. I was told that I could purchase a slide, barrel, recoil spring & rod and convert it to a 40 cal. Is this true, I can not find this in the S&W catalog. Any help would be appreciated.
And let me add, I had it at the range and ran 105 rounds of fmj and hp. Not a single hic-up and accuracy better than I could have hoped for. Loved this gun and could not be happier with it.
Frank.

 

[noluck7]

Nope. You can only go down from .40 or 357 to 9mm. There have been several posts on this. Check out this one:

http://smith-wessonforum.com/smith-wesson-m-p-pistols/234625-m-p-40-option-use-9mm-barrel.html

 

[Houdini1953]

Sorry but the opposite is true you can purchase a A.40 caliber M&P and use either a 357 Sig or a 9 millimeter barrel by Smith & Wesson or Storm Lake and possibly another barrel manufacture but not the other way around.

I own the 9 full size as well as the 40 compact and also the 45 full size and the same holsters from Black Hawk or Minotaur all fit all three guns so do what I did and get another M&P when you budget allows it, I now have a barrel on order for two Storm Lake barrels to convert my 40C to a 357 Sig!

 

[WR Moore]

OK, despite the confusion of the earlier posters, you can convert a 9mm to a .40 by installing a complete .40 S&W slide assembly (barrel, slide and recoil spring assembly). You may need .40 magazines too, varies by how closely the 9mm mags are to blueprint specs.

BTW, the recoil spring assembly for all but the .45 is the same, but they're inexpensive and it just makes sense to have the complete slide assembly ready to go.

What you cannot do is convert the 9mm to .40 by installing a .40 barrel in the 9mm slide ( Not a good idea even if it fit, the 9mm slide is lighter and if used with a .40 would have excessive slide velocity.). This is how they manage to use the same recoil spring assembly with all the 9mm/.357 Sig/.40 S&W guns of the same size.

 

[Helderberg]

OK, despite the confusion of the earlier posters, you can convert a 9mm to a .40 by installing a complete .40 S&W slide assembly (barrel, slide and recoil spring assembly). You may need .40 magazines too, varies by how closely the 9mm mags are to blueprint specs.

BTW, the recoil spring assembly for all but the .45 is the same, but they're inexpensive and it just makes sense to have the complete slide assembly ready to go.

What you cannot do is convert the 9mm to .40 by installing a .40 barrel in the 9mm slide ( Not a good idea even if it fit, the 9mm slide is lighter and if used with a .40 would have excessive slide velocity.). This is how they manage to use the same recoil spring assembly with all the 9mm/.357 Sig/.40 S&W guns of the same size.

Thanks for the information. Would I contact Smith or an aftermarket supplier for the parts? I also wonder if after all the parts needed would it be as costly to just buy another gun in that caliber? Thanks for the replies, I appreciate it.
Frank.

 

[Dave686]

I also wonder if after all the parts needed would it be as costly to just buy another gun in that caliber?

There you go....
Just buy another one.

 

[jaykellogg]

On the S&W site the slide assy (w/sights) is $226.32 and the barrel is $104.29. It appears there is almost zero savings to convert as you suggest. Later, if you decide to trade the pistol the "extra" parts would be difficult to market. The only advantage i can see is avoiding hassles with pistol purchase requiremets. In NC, the purchase requirements aren't too bad

 

[Capt Crunch]

Yeah, it's one thing to be buying a new barrel but when you get into the slide barrel and mags, you might just want to get another pistol. Or trade in the 9 for a .40 and turn around and buy a 9 barrel.

 

[Helderberg]

I think this thread has convinced me that if I want a 40 I should buy one. I will keep the 9 as I like the cost per round, controlability even with +p and more than enough to stop an intruder. I live in a populated area so overpenatration has to be a consideration. If I need power I have my 686 to fall back on. Thanks for all the helpful replies and a great forum.
Frank.

 

[handgunner356]

The small gain of the best 40 compared to the best 9mm isn't worth losing sleep over.

 

[Tyrod]

M&P wanna be here. If one can downconvert a 40 or 45 to 9mm with just a barrel change and magazines is there a downside to purchasing a 40 or 45 outside of the cost of the additional barrel(s) and magazines if one wanted all 2 or 3 calibers. I guess what I'm asking is there a large dimensional difference between a 9mm and 40 or 45 M&P frame and/or slide.

 

[jaykellogg]

M&P wanna be here. If one can downconvert a 40 or 45 to 9mm with just a barrel change and magazines is there a downside to purchasing a 40 or 45 outside of the cost of the additional barrel(s) and magazines if one wanted all 2 or 3 calibers. I guess what I'm asking is there a large dimensional difference between a 9mm and 40 or 45 M&P frame and/or slide.

The M&P45 is a stand alone gun. parts will not interchange. There is a big difference between .45acp and 9mm or .40S&W. I suppose you could convert a .45 to .400 COR BON.

Regarding the .40, the base of the ctg. is just a bit larger than the 9mm. but apparently it'll work. Some folks use the 9mm ammo in the .40 cal magazines, but the mags. will interchange in the grip frame. BTW, this is why the .40 will convert to 9mm but 9mm won't convert to .40. Unless you do as the OP suggested and also buy a slide assy.

 

[Houdini1953]

There you go....
Just buy another one.

This is one of the main reasons I bought a M&P 40C and then next an M&P45, there is nothing wrong with having another gun.

The M&P40 is quite a versatile weapon and the M&P40c is even more versatile in that you can carry a compact weapon and add larger cap mags! Or you can buy a 357 or 9mm barrel and have three guns in one...it should be your first choice in the M&P Line!