M&P 40 to 9mm conversion ?

[tat2dchad]

i am curious....

i have watched every video on youtube i think regarding the barrel swap. i have seen a few videos where they had a problem with failure to eject all the way or cleanly. now my question is and preferably for someone who has experience or has done the conversion and shot it a bunch as both 40 & 9....

using the 40 spring.... do you think its a simple problem of the different spring tension and the 9 mm round just not having enough umph to get that slide to come back far enough and it catches the 9 mm spent casing before it can clear? or... does the M&P 9 stock have the same spring and that theory is 100% wrong?

ive looked all over and like i said watched every youtube video...to the point where i ended up watching cute cats(you know you have done that! dont judge!!) anyways its always better imo to actually have a conversation since the video will never be able to answer a question. so any help or opinions from someone who has experience with this is greatly appreciated

 

[RobzGuns]

IIRC... The 40 and 9 use the same recoil springs (at least in the Shield, they do).
I believe the potential issue lies in the Extractor and Breech Plate recess, as the 9mm has a smaller diameter case than the 40. So if you're simply swapping barrels (as opposed to the entire upper barrel/slide/spring assembly), the 40's extractor may not maintain a good hold on the 9mm case.

This seems to be the general concerns across Brands... Not just the Shield (or M&P in general).
If I'm off, I'm sure someone will correct my recollections.

 

[Woodman90]

I have the M&P 40 and have only around 300 rounds of .40 thru it with zero issues. I have a S&W 9mm barrel with S&W 9mm mags as well as a threaded Storm Lake .40 to 9mm conversion barrel. I have run over 1000 rounds of 9mm between both barrels again with zero issues. Other folks may have other experiences, that is just mine.

 

[Roger S&W]

I was told this recently:
Sounds like you could save yourself a lot of money by buying a 9mm barrel and some 9mm mags and running them in your 40fs. Better yet, buy a 9mm barrel for the compact also and a few xgrips you'll be all set and have lots of money left over for ammo. The 40 and 9mm share the same slide, extractor, and I believe even the same recoil spring.

Nope the dimensions are the same with the M&P.

 

[Morning Star]

This year, I bought the M&P 40 full size pistol before it fell off the California DOJ Roster. Additionally, I bought the Storm Lake 9mm and 357sig conversion barrels. For the 9mm barrel, you need to use the M&P 9mm magazines. For the 40cal and 357sig, you can use the M&P 40 magazines. I've fired a total of 600 rounds (200 - 9mm, 200 - 357sig and 200 - 40 cal) through my M&P 40 without any issues. I found the changing the barrels to be very easy. I used the same factory recoil spring assembly that came with the gun. The 357sig barrel was difficult to locate. You'll have an easy time finding the 9mm barrel. I am very satisfied with my M&P 40 and the ability to use 9mm for training and 357sig for fun.

 

[uechikid]

Factory 9mm barrels are nearly impossible to find, so after market like the Storm Lake is what you'll have to go with right now. If you need a 10 round mag, forget it, unless you want to pay double or tipple the oem price.

 

[Roger S&W]

This year, I bought the M&P 40 full size pistol before it fell off the California DOJ Roster. Additionally, I bought the Storm Lake 9mm and 357sig conversion barrels. For the 9mm barrel, you need to use the M&P 9mm magazines. For the 40cal and 357sig, you can use the M&P 40 magazines. I've fired a total of 600 rounds (200 - 9mm, 200 - 357sig and 200 - 40 cal) through my M&P 40 without any issues. I found the changing the barrels to be very easy. I used the same factory recoil spring assembly that came with the gun. The 357sig barrel was difficult to locate. You'll have an easy time finding the 9mm barrel. I am very satisfied with my M&P 40 and the ability to use 9mm for training and 357sig for fun.

Hope I don't get lambasted for changing subject here for a second but I'm curious. When a firearm "drops off the CA DOJ roster" does that mean it becomes illegal to own? For those that owned it prior to the drop, are they grandfathered in?

 

[tat2dchad]

Yeah..I got lucky and got one off a super cool forum member, really fair price..not S&W good but better than storm lake and ebay prices.i wont complain. 10 round mag??why so little? I jusr ordered a 32 & 17? Whatever fits in the mag well

 

[uechikid]

Hope I don't get lambasted for changing subject here for a second but I'm curious. When a firearm "drops off the CA DOJ roster" does that mean it becomes illegal to own? For those that owned it prior to the drop, are they grandfathered in?

As of right now it is legal to own and transfer (via private party transfer) off roster handgun.

 

[bikendan]

i've had my Storm Lake 40 to 9 conversion barrel for over a year now and have shot over 1000 rds of 9mm.
i've had no problems except with some Tulammo steel case 9mm ammo. about 3 FTE's.
i've no problems with any other 9mm ammo, even Tulammo's BrassMaxx ammo and Freedom Munitions' reload 9mm ammo.

i'm very glad i bought the SL conversion barrel, instead of the OEM 9mm S&W barrel.
it fits the breech perfect and looks cool in silver.

 

[Morning Star]

Factory 9mm barrels are nearly impossible to find, so after market like the Storm Lake is what you'll have to go with right now. If you need a 10 round mag, forget it, unless you want to pay double or tipple the oem price.

I agree with you that factory 9mm barrels are out of stock with MidwayUSA and Brownells. My post was for availability of the Storm Lake aftermarket 9mm barrel which you can at many dealers. S&W "The Store" sells 9mm 10 round magazine for $41.82, but is out of stock. Cheaper Than Dirt sell the same magazine for $39.33 which is in stock.

 

[Morning Star]

Hope I don't get lambasted for changing subject here for a second but I'm curious. When a firearm "drops off the CA DOJ roster" does that mean it becomes illegal to own? For those that owned it prior to the drop, are they grandfathered in?

Short Answer: In California, if you own a gun that falls off the DOJ roster, the gun continues to be legally owned and you can do a private party transfer. However, you cannot buy the gun from a dealer in state or out of state.

Long Answer:
Effective January 1, 2001, no handgun may be manufactured within California, imported into California for sale, lent, given, kept for sale, or offered/exposed for sale unless that handgun model has passed firing, safety, and drop tests and is certified for sale in California by the Department of Justice. Private party transfers, curio/relic handguns, certain single-action revolvers, and pawn/consignment returns are exempt from this requirement.

 

[formernuke]

KKM conversion barrel here. A couple of hundred rounds of 9mm and probably about 1000 of 40. I have no problems at all with the 9mm and 9mm magazines. The only thing I change is the barrel and magazine.

 

[uechikid]

I agree with you that factory 9mm barrels are out of stock with MidwayUSA and Brownells. My post was for availability of the Storm Lake aftermarket 9mm barrel which you can at many dealers. S&W "The Store" sells 9mm 10 round magazine for $41.82, but is out of stock. Cheaper Than Dirt sell the same magazine for $39.33 which is in stock.

Interesting that Cheaper Than Dirt show the 10 round mags in stock. I think you'd be hard pressed to find them any where else. $39.33 plus $14 s&h. But I guess if you really need a mag that's better than paying ebay prices.

 

[tectrry]

I've been using a stock S&W 9c barrel in my 40c for about a year now and probably shoot 3:1 each time at the range (150 9mm to 50 .40 each week) making the barrel swap in a few seconds while reloading. I have never had an ejection problem or a recoil spring issue. It has been flawless. I would only buy .40 M&Ps from now on and get a 9mm barrel & mags even if i had to wait a while for them.

 

[robkarrob]

Same here, a Shield 40 and using the Shield factory 9mm barrel since November 2012. Never had any issues using the 9mm barrel, and with my Shield, the 9mm cartridges feed perfectly using the 40 mags.

Bob

 

[tat2dchad]

I've been using a stock S&W 9c barrel in my 40c for about a year now and probably shoot 3:1 each time at the range (150 9mm to 50 .40 each week) making the barrel swap in a few seconds while reloading. I have never had an ejection problem or a recoil spring issue. It has been flawless. I would only buy .40 M&Ps from now on and get a 9mm barrel & mags even if i had to wait a while for them.

Great post and thanks. What round do you shoot?

 

[shawn mccarver]

i am curious....

i have watched every video on youtube i think regarding the barrel swap. i have seen a few videos where they had a problem with failure to eject all the way or cleanly. now my question is and preferably for someone who has experience or has done the conversion and shot it a bunch as both 40 & 9....

using the 40 spring.... do you think its a simple problem of the different spring tension and the 9 mm round just not having enough umph to get that slide to come back far enough and it catches the 9 mm spent casing before it can clear? or... does the M&P 9 stock have the same spring and that theory is 100% wrong?

ive looked all over and like i said watched every youtube video...to the point where i ended up watching cute cats(you know you have done that! dont judge!!) anyways its always better imo to actually have a conversation since the video will never be able to answer a question. so any help or opinions from someone who has experience with this is greatly appreciated

It is not contemplated by S&W that a barrel swap is an accepted conversion between any two calibers except for .40 S&W and .357 SIG. Those two calibers even use the same magazine.

Attempting to use 9mm in a .40 slide works mostly ok, but the issues you see in the videos you watched have to do with the slop caused by the fact that the 9mm and the .40 have different case head dimensions. They are not much different, which is why it sort of works sometimes. But, it must be understood that doing so should be strictly reserved for the plinking range only, and not for a match or for self-defense, where such a failure could mean disaster.

S&W does not approve of doing such "conversions" from .40 to 9mm. That, however, does not seem to matter to most of the people who attempt it or do it. If you do it, you should also use the magazine of the correct caliber. The last time I checked the parts numbers, the recoil springs were the same for both 9mm and .40, but they may have changed. I am simply not sure of that.

 

[tectrry]

Great post and thanks. What round do you shoot?

Mostly Freedom Munitions (reman or new brass) or HSM. They are the cheapest things that I can usually find for the range. But I also put some Hornady HST through them to make sure it likes them for HD/SD and soon for carrying (my CCW should come through any day now).

I guess I should add that I will be carrying as a 40.

 

[Savannahshooter]

I have the M&P 40c and initially I tried a S&W 9mm barrel and had some eject problems. I since have changed to a Storm Lake 9mm barrel and so far zero problems in 800 rounds of 9mm consisting of FMJ reloads, FMJ and up to 124 grain HP.