Converting M&P 40c to 9mm

[LOBONCA]

I read somewhere that you can convert an M&P 40c to a 9mm by using a Storm Lake 40SW TO conversion barrel kit.
BARRELS SLBSWMPC9C358
STORM LAKE BARRELS S&W M&P COMPACT 40SW TO 9MM CONVERSION BARREL KIT - SLBSWMPC9C358

Is there any trick to this? or is it just a matter of inserting the 9mm barrel?

My main reason is to save money at the range. But continue to use the 40 cal for carry.

 

[Carnage_7]

Can be done-also have to buy the 9mm mags though!!!

 

[LOBONCA]

Other than getting the 9mm mags, is there nothing more to do than put the new barrel in the frame?

 

[OKFC05]

While the conversion barrel is designed as a drop-in, there is no absolute guarantee that it will. My gunsmith tells me there have been a few that needed a touch of fitting. If you have any problems, you can discuss them with Storm Lake before taking it to a gunsmith. If you don't have any problems, then happy shooting!

 

[Knochen]

"you can discuss them with Storm Lake before taking it to a gunsmith"

For an advertised drop-in barrel, I sent my SL 9 mm barrel back twice to them before I could even chamber a bullet. My take is that you shouldn't have to take it to a gunsmith, particularly given how popular this particular barrel is, it should be made right. They paid for shipping, but it took at least 2 months before I had a working barrel. With the cost of ammo, I am now a happy camper at the range. It fires all day with no problems. I bought the FS 9 mm mags with X-grips, so I have less time loading.

 

[Simmy952]

I just purchased a complete top end with a few mags. Works fine for me. I was going from a 9c to a 40c. 40 & 357 Sig can be done with standard barrel changes and the mags are the same. 40 to 9 has to have a conversion barrel or different top end.

 

[PD Sgt.]

I use a factory S&W 9mm Compact barrel in my 40c with 9mm magazines. While I would not depend on it for defensive purposes, I have probably put close to 1K practice rounds through it without any problems.

I measured the barrels against each other with digital calipers and they were within a few thousandths in all critical dimensions.

 

[Lost Lake]

There is a good write up if you search for it where the guy compares two factory barrels and they are so close that many just drop in a factory 9mm for $65. I have heard about more problems using the Storm conversions than a factory 9mm barrel, but maybe more people try the Storm barrel, I don't know.

 

[ipittythefoo]

I have had no issues with my factory 9mm barrel

 

[cpippen]

I have a 357c and use the 40c factory barrel in it. I also have a factory 9c barrel I use. There has been no problems for me thus far. Of course you have to get magazine for the 9mm. I will carry any of them as my defense rounds. However, that being said I mainly carry 357 just because I like the round for my needs and wants. Would I feel scared carrying my 9mm barrel in my 357 not at all. Plus the factory barrels are cheaper and drop in.

 

[revolvergeek]

I have no experience with the C, but my MP40 runs 9mm great with just a factory 9mm barrel and mag installed. 100% reliable with 115 and 124 FMJ so far (I have not shot any JHP through it because I just intend this as a cheap practice setup).

 

[patchdoc]

Using stock 9mm (c) barrel in 40c

There is a good write up if you search for it where the guy compares two factory barrels and they are so close that many just drop in a factory 9mm for $65. I have heard about more problems using the Storm conversions than a factory 9mm barrel, but maybe more people try the Storm barrel, I don't know.

What about the recoil spring. Doesn't the spring for the 40c expect more recoil force to cycle properly?

 

[Johnmuratore]

Nope. the .40c and the 9c use the same recoil spring.
Yellow end.

 

[wdk535]

I just purchased a complete top end with a few mags. Works fine for me. I was going from a 9c to a 40c. 40 & 357 Sig can be done with standard barrel changes and the mags are the same. 40 to 9 has to have a conversion barrel or different top end.

When you say "top end" do you mean the slide assy., with barrel and spring?

 

[uechikid]

OP, you might give S&W a call and see if you can buy a factory barrel from them. Depending on who you talk to you might get lucky as I did a few months ago.