Converting a M&P 9mm 4.25" to 40/357

[JackBauer]

Hello,

I read this post from 4 years ago on NES regarding converting barrels on the MnP frame: http://www.northeastshooters.com/vbulletin/equipment/77287-m-p-357-barrel-use-40-a-2.html

Someone does say that the 9 and 40 frames are the same but the uppers are not. My goal is to take my 9mm and make it more versatile by being able to use 40/357 as well.

What is the cost and where would I go about getting parts to put a 40 upper on my 9? Per the post I need: "Just a slide, barrel, and recoil guide/spring assembly."

I'd like to first go to 40 and then do 357 down the road.

Thanks all,
JB

 

[finest]

To convert an M&P from 9mm to 40s&w you would need to get a complete slide assy and barrel,and would also require the appropriate caliber magazine, with both 40s&w and 357sig utilizing the same magazine. I started with the 40 and just bought a 9mm barrel and a couple mags, and now my 12yr old daughter gets to use it as well. Good luck on your quest

 

[dcmdon]

+1
.40 to .357 or 9, no problem. But not the other way.

The .40 slide has a bigger hole in it among other things...

 

[JackBauer]

+1
.40 to .357 or 9, no problem. But not the other way.

The .40 slide has a bigger hole in it among other things...

If the frame is the same...I see no difference in putting different uppers on. I'm just trying to find out how to get it done.
I'll call S&W.

 

[dcmdon]

You can put a different upper on typically. But you will need a new slide.

Going rhe other way, all that's needed is a conversion barrel.
A conversion barrel has the larger exterior dimensions of the 40/357 barrel with a 9mm chamber and bore.


One side effect of a conversion barrel is a thicker barrel wall.
I own a .40 Gen 4 Glock 35 with a Storm Lake 9mm conversion and its noticeably heavier than my wife's otherwise identical 9mm Gen 4 Glock 34.

 

[SJan]

You can get conversion barrels from Storm Lake to shoot 9mm and 357 out of a 40 gun. Can't go the other way around. Its difficult to find a slide assembly for sale, but not impossible. If I were you, I would buy another gun in a different caliber.

- - - Updated - - -

A conversion barrel has the larger exterior dimensions of the 40/357 barrel with a 9mm chamber and bore.


One side effect of a conversion barrel is a thicker barrel wall.
I own a .40 Gen 4 Glock 35 with a Storm Lake 9mm conversion and its noticeably heavier than my wife's otherwise identical 9mm Gen 4 Glock 34.

This is why conversion barrels are not legal for USPSA production class, it is essentially a barrel weight

 

[dcmdon]

There are regularly guys selling complete upper Glock 22 slides on GB. They go for between $325 and $375. You can guy an entire brand new Gen 4 glock for $485.

I was not even able to find an M&P slide on GB. So if one does become available, chances are that it will go for more than the Glock slide.

This is why conversion barrels are not legal for USPSA production class, it is essentially a barrel weight

Yup. They're not legal in IDPA either.