Question for M&P owner/guru's

[Builder Bob]

I am looking at a full size M&P and was considering getting it in .40 The question is if you can put a 9mm barrel into a .40 and all still work with a magazine change of course? Also, would I have to change the recoil spring?

Thanks

Builder Bob

[wcsc12]

I am looking at a full size M&P and was considering getting it in .40 The question is if you can put a 9mm barrel into a .40 and all still work with a magazine change of course? Also, would I have to change the recoil spring?

Thanks

Builder Bob

I think if you're looking to do that kind of stuff, you may just want to go the Sig P250 or P226 route and buy a Caliber X-Change Kit. They are around $200 but have the entire slide and a magazine for switching between calibers and the best part is that they should come with nightsights except the 22LR which doesn't.

Opinion over.

To answer your question. No idea at all but if it's like any other gun, no should be the answer. Generally, at least with all the guns I've seen, a different slide is required because of the difference in recoil, ejector shape/size, and something else...I think it's the way the barrel lines up to the firing pin but I could be wrong about that. The only Guns I know that can do something like are the Sig 40's in which you can just drop in the .357 Sig barrel and still use the same slide and magazine.

Edit: Found you some information via Google.

http://smith-wessonforum.com/smith-wesson-m-p-pistols/209960-m-p-40-357sig-9mm.html

Apparently, according to these posts, sometimes it works and sometimes it doesn't but it's not S and W recommended to do it.

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.

Edited October 26, 2011 by wcsc12

[Smith]

Yes, you can get a 9mm or 357 SIG conversion barrel and it will work in the .40 slide. It has to be a conversion barrel and not just a standard barrel to work. As far as the recoil spring you may want to change springs but it is not mandatory. The only thing it might do is not cycle light load 9mm.

[Guest motonut]

I have 9mm conversion barrels for a couple of my (40 cal) guns. XD40 & Sig 229. Not a lick of problem with either of them. IIRC the barrels are EKT (or ETK?). I got them because I had shoulder problems a couple of years ago that eventually required surgery. Hurt like the dickens to shoot a 40, the 9mm hurt a little less. Now I leave them in just because the ammo is cheaper.

No problem with the original slide on either gun.

[Smith]

I have 9mm conversion barrels for a couple of my (40 cal) guns. XD40 & Sig 229. Not a lick of problem with either of them. IIRC the barrels are EKT (or ETK?). I got them because I had shoulder problems a couple of years ago that eventually required surgery. Hurt like the dickens to shoot a 40, the 9mm hurt a little less. Now I leave them in just because the ammo is cheaper.

Probably EFK Firedragon. Good barrels. I have used them a number of times.

Pistol and Gun Accesories | EFK Fire Dragon

[Guest motonut]

Probably EFK Firedragon. Good barrels. I have used them a number of times.

Pistol and Gun Accesories | EFK Fire Dragon

Yup, that be it.

This gettin' old is for the birds. Beats the other option though.

[Builder Bob]

Very good info, I thought I had heard that you could do that but wanted to ask about results in the real world. I had thought about getting one in .40 and could switch up with 357 sig and the conversion 9 barrel.

[Trekbike]

Interesting that you brought this up. TGO member DAdams had a post reply to another M&P thread the other day and mentioned he had bought a 9mm conversion from Storm-Lake. I've got a PM into him to see how it worked. You can go their site and build the barrel just like you want (within their normal options).

NOTE: you have to choose the 9mm conversion barrel, not the standard 9mm barrel.

StormLake | Barrels built for accuracy

[DAdams]

Unfortunately I haven't had a chance to try out the conversion. Storm Lake is located in Lenoir City just up the road from me. I spoke with them on a couple occassions and swapped a couple of emails. They said the .40 to 9mm barrel is a "drop-in" replacement and no modifications were required (the right magazines must be utilized). Before making the buy I researched and communicated with owner/users on the S&W Forum and the M&P Forum. My confidence is high that this will work, but practical experience has yet to take place, and I am by far not an M&P Guru. I just own a couple.

Edited October 30, 2011 by DAdams

[DaveTN]

Looks to me like buying a new barrel and two M&P mags would be half the price of a new gun. I would invest the extra money and have two guns….. but that’s just me.

[TNWNGR]

Yes, that is the more practical way to look at it, the same applies to having more than one upper for an AR-15 or clone as well. Still, the ability to change calibers with a barrel and magazine change is pretty cool, H&K played that line pretty heavy with the H&K 4 and it’s too bad it was a poor quality flop. 9x19 ammunition is less expensive than .40 S&W so it is conceivable a person could come out enough ahead to do ok in the end.

[DAdams]

Looks to me like buying a new barrel and two M&P mags would be half the price of a new gun. I would invest the extra money and have two guns….. but that’s just me.

I have a 40c and 9Pro. I can use the magazines from the 9 in the 40 with the conversion barrel. The 50% point isn't quite 50% when you already have a half dozen 9mm mags albeit full sized ones so on can let them hang or put XGrips on if it's a C.

Since the Storm Lake is a "match barrel" you might even get better accuracy.

Edited October 31, 2011 by DAdams

[Guest motonut]

IIRC on both my XD and Sig the mags for the 40 and .357 Sig are the same but you need 9mm mags for 9mm (.40 mags aren't recommended w/ 9mm).

Maybe the M&P is different (I kind of doubt it myself).

[Mark A]

IIRC on both my XD and Sig the mags for the 40 and .357 Sig are the same but you need 9mm mags for 9mm (.40 mags aren't recommended w/ 9mm).

Maybe the M&P is different (I kind of doubt it myself).

226 & 229 are the same. 239 uses dedicated caliber mags.

[DAdams]

M&P .40/.357 SIG are interchangeable but NOT 9mm.

[Builder Bob]

After looking and pondering I think it will be easier to go with two separate guns instead of going with the conversion barrel. Of course I have not bought anything yet so it is subject to change.

[Smith]

After looking and pondering I think it will be easier to go with two separate guns instead of going with the conversion barrel. Of course I have not bought anything yet so it is subject to change.

Good call IMO.

[NRA]

After looking and pondering I think it will be easier to go with two separate guns instead of going with the conversion barrel. Of course I have not bought anything yet so it is subject to change.

thats what I did