From M&P .40 to 357SIG to 9mm

[WillyM&P]

Being new to Smith & Wesson's M&Ps pistols, and a recent owner of my first one (.45 ACP), I thought I had read somewhere that if you purchase the one chambered in .40ACP you can also use the same pistol to shoot 9mm rounds if the 9mm barrel and magazines are acquired.
Now, this is not just any 9mm barrel from S&W, it has to be a conversion kit or conversion 9mm barrel which seems to be available only from a third party company such as Stormlake's conversion kit.

While S&W says that you cannot put a 9mm barrel in a .40ACP M&P pistol, they are saying that you can put a 357 SIG barrel and magazines instead. From what I gathered, no need for a third party conversion kit here, the S&W stock 357 SIG barrel would do the trick.

Did I understand this correctly?
If so, than this would be like having 3 M&Ps for the price of one pistol plus whatever the other two barrels cost along with their respective magazines.

Has anyone tried this, going from a .40ACP to a .357SIG and / or 9mm?

Did you have to do any gunsmithing at all?

How accurate is it once you switch to .357SIG and 9mm.?
I am thinking about getting another M&P chambered in the .40ACP for this reason only, so your input and advice would be greatly appreciated.

Thank you.
Wil

 

[OKFC05]

.40 S&W to .357 is a snap, since only the barrel changes, and it actually fits.

However, 9mm does not actually fit the breech and .40 extractor, but usually a conversion barrel is close enough to work; NOT always.
IMHO, the conversion barrels are close enough for range blasting, but I don't trust .020 misfit for serious work. If you get a conversion barrel that is unreliable, don't modify the gun to fit the mule barrel.

Also, if you intend to shoot stock/production competition, conversion barrels are NOT allowed.

 

[WillyM&P]

Thanks.
Can you still get away with using the .40ACP mags with .357 SIG rounds?

 

[OKFC05]

Thanks.
Can you still get away with using the .40 S&W mags with .357 SIG rounds?

Exactly the same mags

 

[El Fumador]

Welcome.

The mags come stamped with both calibers on them.

 

[Lost Lake]

Guys beat this to DEATH.....

Search this forum for 40 - 9mm conversion and you'll find guys that use the STOCK 9mm barrel in a 40 gun and it works flawlessly. Better than some Storm conversions that cost twice the price.

A stock 9mm barrel can be had for $65.

The .40 magazines will even work with 9mm shells but the last round may not feed as the action may lock open.

Some folks push the Storm barrels like they have stock in the company. For my money, the Storms have had problems and guys here have documented them. I haven't read of anybody having problems using a stock 9mm barrel in a .40 frame yet.

If you have please let us know.

 

[hberttmank]

What is the 40ACP? Not familiar with this round at all.

 

[Dragon88]

There is no 40 Automatic Colt Pistol, though just typing that out gets my brain spinning! Oh the possibilities.

He meant 40 S&W.

 

[vercengetorix]

How about a stock 9mm barrel fitting into an M and P 357sig gun...?? This is confusing.....lol.......maybe I should just call S and W customer service.....lol

 

[OKFC05]

How about a stock 9mm barrel fitting into an M and P 357sig gun...?? This is confusing.....lol.......maybe I should just call S and W customer service.....lol

S&W wil tell you that .40 S&W & .357 interchange, and tell you NOT to put a 9mm barrel in either, because of the mismatch with the breech and extractor. They don't want you to complain if it does not work.

However, it usually (not always) works well enough for range blasting, although people like me will caution you there is a small misfit.
And brother, that's as good as you're going to get, because S&W will NOT guarantee the 9mm barrel to work in anything besides the 9mm gun.
And buying an expensive 9mm conversion is no guarantee it will always work either: most do, some don't.

My personal choice was to buy a separate 9mm M&P (or 2) because if you buy a $200 conversion barrel and 3 9mm magazines, you're 2/3 of the way to a whole pistol, and if you have to pay to have the conversion custom fit to yur gun, you've paid for a whole gun.
IMHO, sometimes this " shoot all calibers out of one gun" can get past practical.

 

[turbo38gn]

Not sure about others that have posted a response to this thread, but I actually have purchased the extra barrels, love my 9mm Storm\Lake barrel, has worked flawlessly and is just as accurate as my original 40fs barrel. I wouldn't think twice about doing it again. In fact, I plan to get another barrel for my compact 40. I also purchased a 357sig ported barrel from Storm\Lake for my 40c. I've only shot about 100 rounds through it, didn't care for it. The gun functioned fine, the barrel functioned fine, but the recoil seemed violent, I had a difficult time with accuracy, which I attributed to my gun control. When I secured my arm on the table as best I could, I was able to close it up. I think I'll have to work on the 357 again, I stocked up on some ammo, just have to get to the range and try it again. Here's a couple pics of my 357 sig S\L barrel'

Since I have both compact M&P's, a 9mm and a 40c, I can try the S&W 9 in the 40, just not sure I really want to do it, but maybe I will..... as for stock in S\L...