M&P 9mm ... A couple of questions

[Rich1911]

Hi folks,

I am considering buying this handgun, http://www.cabelas.com/product/Shoo...nknown;cat104792580;cat105526980;cat105529680
It is available in .40 or 9mm.
I originally wanted it in 9mm since I don't have a 9mm but after some research I found that if I get the .40 instead I can buy this barrel http://www.midwayusa.com/product/150824/smith-and-wesson-barrel-s-and-w-m-and-p-9mm-luger and use the .40 magazines that come with the gun.
Has anyone done this and how well does it work? I read a couple of reviews that said while it works fine with the barrel sometimes there could be an issue with the .40 magazines not feeding the last round. Can anyone confirm or deny this. I know I can buy 9mm magazines but haven't been able to find any with bottom plate matching the tan color. I would rather buy ait in 9mm and buy a .40 barrel but that is not possible from what I have found. Thanks for any help.

 

[BradMacc82]

Can you shoot the 9mm in a .40 slide with just a barrel swap? Yes.

Is it suggested by our resident (soon to be retired) gunsmith? No.

I forget exactly why he doesn't recommend it, but maybe he'll pop in and refresh our collective memories.

If you want it in 9mm, get it in 9mm.

 

[Boom Boom]

As just said above, if you want 9mm, get 9mm. If you want .40, then stick with .40. Being able to use a 9mm barrel and mags with the .40 doesn't make it reliable. It might be fine for limited use at the range, but that's it. If you get the .40, forget the extra 9mm barrel and mags and use the money saved for ammo or something else. Or buy one M&P in 9mm and one in .40.

I suggest never using .40-marked mags for 9mm, even if it technically "works". There's too much risk of losing track of exactly what's what and doing something dangerously stupid.

There are other threads in the forum about people wanting to do the same thing with Glocks, along with strong reasons why it's not the best idea.

 

[NIK]

Funny you mention the 9mm conversion... As soon as I read your dilemma of 9mm vs. 40, i was going to suggest just that! I'd absolutely get the 40 and 9mm conv. barrel. You have the benefit of a powerful .40 cartridge and have the flexibility and economy of a 9mm for extended range sessions. I have 9mm conversions for my Glock 22, Sig P229 and Sig P239. I've fired thousands of rounds from them and never had an issue when I used the appropriate 9mm magazine. You CAN use the .40 mag, but it will not feed reliably past 6 or 7 rounds, so buy the extra mags unless you just want range time.

I'm not sure if you can simply swap out a 9mm barrel though... You should get a conversion barrel. The diameter of a .40 is slightly larger than the 9mm barrel, so the conversion barrel has the diameter of the .40 but fires the 9mm. This will work (and it's a pretty good price too!)

http://www.midwayusa.com/product/64...o-9mm-luger-1-in-16-twist-425-stainless-steel

Quick disclaimer... I am not a gunsmith, I just speak from experience.

 

[smokey]

the breech face, extractor and ejector are different from 9 to 40(since the 40 has a larger diameter base). You should be able to go from 40 to .357 sig with a barrel swap fairly easily(since the 40 and .357 sig share the same base of the casing), but shooting 9 through a slide/ejector built for a 40 can prove to be unreliable.

The most important thing is to ensure the new part is properly fitted and timed into the gun. You don't want to destroy your existing factory gun with an aftermarket barrel that's not fitted properly.

 

[montoya32]

I think there are other differences in the .40 and 9mm(internally). Last I checked the 9mm case and .40 cal case are different diameters. I would not run 9mm rounds in a .40 cal mag. They will not stack properly and will lead to issues. Maybe not consistent issues, but issues non the less.

 

[NIK]

Maybe they're right, maybe not. All I know is I have several and had zero problems with mine and I've had mine for many years now.

 

[ChrisR/T]

Hi folks,

I am considering buying this handgun, http://www.cabelas.com/product/Shoo...nknown;cat104792580;cat105526980;cat105529680
It is available in .40 or 9mm.
I originally wanted it in 9mm since I don't have a 9mm but after some research I found that if I get the .40 instead I can buy this barrel http://www.midwayusa.com/product/150824/smith-and-wesson-barrel-s-and-w-m-and-p-9mm-luger and use the .40 magazines that come with the gun.
Has anyone done this and how well does it work? I read a couple of reviews that said while it works fine with the barrel sometimes there could be an issue with the .40 magazines not feeding the last round. Can anyone confirm or deny this. I know I can buy 9mm magazines but haven't been able to find any with bottom plate matching the tan color. I would rather buy ait in 9mm and buy a .40 barrel but that is not possible from what I have found. Thanks for any help.

BoTach Tactical has the matching magazine you seek, other than that, I have no info.

 

[oldsarge]

I have the M&P in .357 and bought the .40 barrel to go with it. They both work fine, use the same mags and allow me to shoot .40 at the range and carry .357. I don't know about using a 9mm barrel. I have never tried it but lately the price of .40 has dropped enough to put it close to 9mm. Wallmart in Dunkirk was carrying Federal 100 round bulk packs for $24.00.

 

[alucard0822]

40-9 Conversions can work well, or be a jamtastic POS, some of it is luck, some has to do with the ammo, some with the fit of parts. The barrel is the easy part, most require little if any fitting, and as long as the ramp and lockup geometry is right the barrel will do it's part, being most modern designs have identical outside dimentions on the barrel between 9/40/357, there is minimal fuss. Using mags for a caliber they weren't designed for will cause a problem unless they are modified at minimum, use 9mm mags with the pressed ribs to properly stack ammo for 9mm only, and 40 mags for 40 or 357 sig(same parent cartridge mags are interchangeable), some mags may feed OK in another caliber, most will not. The one part most ignore is the breech face, this is important though, exractors are tuned to place a specific tension on the case. When a wide 40 breech face holds a 9mm rim, it has little if any tension, and extraction is usually the issue you run into with 40-9 conversions, it also allows the extractor to put a side load on the case where the other side of the breech face does not support the case. Normally the case is stripped from the mag, and pushed up the ramp, and the rim slides under the extractor as the riun leaves the mag, and the bullet enters the breech, these 3 points of contact help transfer support and control of the round from mag to breech, but with conversions the extractor grabbing the round is delayed, and weakened, so there can be a point in time where the round is free from the mag, starting to enter the barrel, but not yet held by the extractor. One of 2 things can happen, the round slips to the side, and falls out or jams, or it is pushed by the front face of the extractor, not the hook, and then as it chambers the extractor is slammed into it, springs over the rim, and can damage or cause rapid wear to the case rim or extractor.

You also often have different spring rates to delay recoil, a light 9mm spring set can hammer you in a heavy 40 load, and a heaviier 40 spring may not cycle reliably with light 9mm loads. Most springs are chosen to allow a wide variety of ammo in that caliber to be used, but even in the original caliber youcan often get a better more reliable pistol if the spring is ideal for the load you intend to shoot. If you convert a pistol with a complete slide and mag, you basically have a complete pistol in that caliber, and can convert a 9mm to a 40, or in another case something like a 45 to a 10mm, it will also be reliable by design. The further away you get from that the less reliability you have, use a barrel, springs and mag, you might have issues, don't use a tuned spring, and failures increase, with only a barrel there will be problems. The only exception are calibers designed for a barrel with or without a spring to swap, like 40 to 357sig, 10,, to 9x25 dillon, 45acp to 400 cor-bon etc..

 

[Numidian]

Just get a 9mm and be done with it. Good defensive 9mm loads aren't giving up much to a .40 and you get the nice cheap plinking ammo.

Caliber conversions are not worth the trouble imo.

 

[smokey]

Just get a 9mm and be done with it. Good defensive 9mm loads aren't giving up much to a .40 and you get the nice cheap plinking ammo.

Caliber conversions are not worth the trouble imo.

truth...

 

[Rich1911]

Thanks for the input everybody. I went with the 9mm. Now the wait begins - probably be about two weeks for this one since it has to ship from Cabelas before I can do the paperwork. Someone mentioned something about the barrel link I posted being aftermarket but it was made by S & W. Not that it matters now - just wanted to clear it up. Thanks again and I will post some pics when I get it.