M&P .40 to 9mm conversion

[Expygator]

I have a full size 1.0 M&P .40, 4.25" that I want to convert to 9mm so I can go to one size handgun ammo.

Wish list....I would like to have a longer barrel (4.95-5.01) in polished ss if possible. Without gun modification what are my options?

Overall though, what are my options for converting the FS .40 to 9mm?

This is a home defense, range/recreational, carry in my car when I travel gun.

Thank you

 

[retired2006]

I used a Storm Lake conversion barrel on my 40, that and the 9mm magazines were all I needed. Shoots and functions fine, the sights were even right on ! The barrel I used was a 4.25 ", no extras.

 

[WR Moore]

There are conversion barrels that will do that, you may need 9 mm magazines. I'm not sure if that long a barrel will fit into the original slide.

Right now, the only relatively reasonably priced source of slides for the M&P series is S&W. There are a couple of companies who make specialty slides for the competition folks, but you can buy a whole gun for less.

If you're going to bet your butt on the result, I'd suggest you shop around for a complete 9 mm slide assembly on various websites. Or just break down and trade your .40 in on a 9 mm.

 

[robrossk]

This

I used a Storm Lake conversion barrel on my 40, that and the 9mm magazines were all I needed. Shoots and functions fine, the sights were even right on ! The barrel I used was a 4.25 ", no extras.

This ^^^. There is also a threaded version which gives you another 1/2 inch or so.

 

[mckenney99]

With the shuttering of Remington, owners of Storm Lake, it looks like it is going to be progressively more difficult to find Storm Lake barrels in the secondary market. If you want one and find it, you better buy it.

 

[Expygator]

I found a Storm Lake 9 mm 5" barrel for a 1.0 M&P Pro. It's not a conversion barrel. It's a drop in 9 mm barrel for a 9 mm Pro.

I know the slides are the same size on FS and Pro.

Does anyone know if this barrel will fit my application?


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[swsig]

With the shuttering of Remington, owners of Storm Lake, it looks like it is going to be progressively more difficult to find Storm Lake barrels in the secondary market. If you want one and find it, you better buy it.

Apparently, Stormlake is not permanently out of business. They have been purchased as part of the Remington bankruptcy. Here is an article that explains it all:

Remington Buyers REVEALED - The Cards have Fallen & are Divvied Up

I have one of their .357 SIG conversion barrels in my M&P 40c, and it is excellent. It's a perfect drop-in fit without a bobble in 2,500 rounds. Let's hope they are back in business soon.

 

[mdf9183]

I have an MP1 and 2 that I converted to 9mm. Just a barrel swap and some 9mm mags and your good to go.

 

[Saudade]

I found a Storm Lake 9 mm 5" barrel for a 1.0 M&P Pro. It's not a conversion barrel. It's a drop in 9 mm barrel for a 9 mm Pro.

I know the slides are the same size on FS and Pro.

Does anyone know if this barrel will fit my application?


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I bought one of those too for my 5" 1.0 ported Core. It's not ported. It fits fine in my 4.25" but haven't shot it with the 4.25" slide.

Bear in mind that the width of the hood on the .40 is a bit wider than the 9. Many people still get a stock 9mm barrel for their .40 and it works well enough. You should use 9mm mags.

Also just pointing out the Storm Lake barrels are not 1:10 twist, they are 1:16.

 

[Expygator]

I bought one of those too for my 5" 1.0 ported Core. It's not ported. It fits fine in my 4.25" but haven't shot it with the 4.25" slide.

Bear in mind that the width of the hood on the .40 is a bit wider than the 9. Many people still get a stock 9mm barrel for their .40 and it works well enough. You should use 9mm mags.

Also just pointing out the Storm Lake barrels are not 1:10 twist, they are 1:16.

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[Expygator]

I've been told that the SL barrel is made to same standards as S&W.
So the standard S&W 9mm barrel drops into the .40 frame and slide.

The person selling the 5" SL non-ported barrel for the M&P 1.0 Pro 5"said something about the barrel being flared but since the SL is longer, it actually works.

Does this make any sense? I'm not gun savvy enough to know what it means.

Thx


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[Expygator]

I have an MP1 and 2 that I converted to 9mm. Just a barrel swap and some 9mm mags and your good to go.

Did you use conversion barrels or just S&W 9 mm barrels?


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[Saudade]

I've been told that the SL barrel is made to same standards as S&W.
So the standard S&W 9mm barrel drops into the .40 frame and slide.

The person selling the 5" SL non-ported barrel for the M&P 1.0 Pro 5"said something about the barrel being flared but since the SL is longer, it actually works.

Does this make any sense? I'm not gun savvy enough to know what it means.

Thx


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The 9mm barrel will drop in, subject to the hood dimension difference. Here's a pic showing the difference:



I'm guessing here's the "flare" the seller referred to:

 

[Expygator]

So he said this barrel would work because the flare is longer, vs getting a S&W barrel.

I don't know why though.


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[AppStFan]

Check with KKM Precision for a 40 to 9 conversion barrel. They make a quality barrel and are a good company to deal with.

 

[much ado]

40 to 9 Conversion

I have a 40 Compact(Version 1)and earlier this year was perusing one of the 3 or 4( or 5 or 6) ads I receive weekly from Midway and there was to my surprise OEM barrels advertised. The Compact barrel I bought was $68 I believe, then of course had to chase down magazines but when I got the package together I am surprised at the accuracy of that drop-in barrel. They have/had the full size versions too but I believe they were a little more. In any case check them out. The hood width difference mirrors that shown above. Ejection is a little different as the 40 throws empties over yonder somewhere and the 9 drops them 4-6 ft right...if you reload 9 you will like it. That ejection is(in my opinion) pretty likely unless you get a 9 slide. Hope this helps, John