M&P 40 S&W to 9mm Conversion w/ KKM Barrel

It is a slight chance you take. I bought a M&P .40 FS and inspected and shot it enough with the .40 barrel to prove to my satisfaction that it was not problematic and probably wouldn't need warranty work. I would think S&W would have the prove the problem was due to a conversion barrel before it voided the warranty. If the problem wasn't barrel related, S&W would still have to fix it.

Before I shot the M&P with the conversion barrel, I thoroughly checked to make sure it fit properly. If the conversion barrel has a problem, KKM will take care of you on the barrel - maybe the pistol if the barrel caused the problem.

I wouldn't hesitate to do it again. Glock will probably have the same policy. S&W wants to sell 2 handguns not 1.

Many on this forum just buy the factory 9mm barrel and have good results. I bought the KKM conversion barrel just to ensure good fit and function and because I have had good results with KKM barrels before.
 
The factory 9mm barrel actually works better than the aftermarket barrels do.

Anything you do will void the factory warranty. Polishing the trigger, filing the burr off the takedown lever, and yes, swapping out the barrel.

Hundreds, maybe thousands of M&P 40's are using M&P 9mm barrels, with hundreds of thousands of rounds fired with no problems.

As Nike says.... Just Do It!!! :D

.
 
Lost Lake said:
The factory 9mm barrel actually works better than the aftermarket barrels do.
Click to expand...

Prove that statement. My KKM 40-9 barrel works 100% and is very accurate. It fits the breechface perfectly unlike a factory 9mm barrel which produces a slight gap at the top.

M&P 9mm barrels have been criticized for accuracy problems up until recently when S&W changed the twist rate and design.
 
Regardless of going with OEM 9mm or KKM Conversion, I assume were using S&W OEM 9mm mags?
 
In my opinion the best and least expensive way is to buy the s&w 9m barel and 9mm mag and u are golden best reliability
 
Everyone has their own strong opinion either buy S&W OEM Barrel or KKM/Storm Lakes conversation Barrel. The people who spent a lot of money for KKM justity for what they spent or the ones who purchase OEM Barrel by S&W because it is by the manufacturer both have strong points. You need to do what you feel makes you comfortable and you will have great S&W before and after the change. I personally went with OEM route since the OEM guts have the same item numbers so I felt that as a manufacturer it customary to build transferable parts to keep cost down and more practical for quality control. If you research on this and other S&W forums your S&M
W brothers have shot thousands of rounds through OEM barrels with no ill effects and no accuracy problems. But again do what is best for you. It is your semi auto and only you who will practice with it. I personally convert my back to .357 for EDC. Rowlette
 
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Not to throw another option into the mix but does anyone have thoughts or recommendations on Storm Lake's vs KKM conversions? From what I know, Storm Lake has standard rifling, matched grade barrel and ported/threaded options which can shoot lead, FMJ and reloads. The KKM has button rifling which they say is better but I'm not sure on matched grade barrel or if it's capable of firing lead, FMJ and reloads. Waiting on call back from KKM.
 
I had two CHL students shoot 50 rds through my M&P FS .40 with the KKM 40-9 conversion barrel and a 9mm magazine for the shooting qualification part of the class last Saturday (5/25/13).

The students experienced perfect feeding and function with all 100 rds fired.

Interestingly, I gave three inexperienced students the opportunity to handle my M&P FS and Glock 17 and choose the one to shoot during the CHL shooting proficiency test. Two chose my M&P and one chose the G17.

After the shooting test, I took the M&P apart and inspected the slide and conversion barrel. There was no unusual wear or damage to either since I started using the barrel.

BTW, I don't feel any need to justify the expense of buying a more expensive 40-9 conversion barrel over the stock S&W 9mm barrel. I am reporting on the performance of the KKM barrel for anyone interested. To each his own.
 
I have a new M&P .40 Pro with the KKM conversion 9mm barrel. I am using factory M&P 9mm mags and have all kinds of problems with. I have tried about 4 mags of ammo using two different factory 9mm mags and experienced all three types of failures; failure to feed, failure to eject and double feeds. I haven't tried it yet with the .40 barrel and .40 mags and ammo. I never had this with my G22 conversion. Help!
 
Sorry to hear about your problem. Does the barrel fit the slide well - not too tight or loose? Does the slide hand cycle okay with the KKM barrel installed? Shoot the pistol using the factory 40 barrel and see if the pistol is working okay otherwise.

You are probably going to have to call and possibly send it back to KKM.

I have had perfect reliability out of my KKM 40-9 conversion barrel. I'm sorry you have had a problem. Sounds like you are trying all the right things.
 
9mm conversion

Bret said:
How much does a barrel cost directly from S&W?
Click to expand...

I bought a oem S&W 9mm barrel from Midway USA last month for $66.99. They're currently out of stock but can be backordered. Don't know how long the BO is.

Put the barrel in my M&P 40 and shot 50 rounds with the .40 magazines. Noticed that I had to make sure to seat the first 9mm round good in the .40 magazine or else the slide locked back with that last round still in the magazine. Other than that it shot great.
 
I called S&W direct to ask about this and was told they are not selling the barrels separately right now. They are being held for production, and to not expect to see them on the market for another 6 months.......

Looks like I will be looking for an aftermarket one as M&P owners selling on the various forums have proven very unresponsive and unreliable unfortunately. :confused:
 
Thread .40 to 9mm Conversion Barrel

I opted for the threaded version of the barrel and it has worked out great. It fits the slide extremely tight and shoots straighter than I can. I heard S&W is keeping all 9mm barrels for production and not selling any to the public. KKM is more but you won't be disappointed. I bought the 9mm magazine for mine and have not had an issue with it. In fact I think the 9mm barrel might even shoot a little straighter than the .40 does, they both shoot great. Keep in mind that S&W made two styles of barrels, one with and one without a collar by the chamber. KKM sells the newer style. If you have a barrel with a collar you may want to get the Storm Lake barrel which MidwayUSA sells.
 
Start configuring M&P, 40 cal barrel. Select the size, then look in the OPTIONS drop down.

There it is.

KKM.jpg


Dave
 
Just ordered one direct from KKM - sticker shock for sure. My wife has a 40c - this will give her a chance to see if she likes the 9mm. Now to find a couple of mag's
 
KKM 40-9mm conv. Bar. SAME SPRING ????

Like the Post indicates, I just got my new KKM 40-9 mm Conversion barrel but I never thought of the Spring until I was actually installing the new barrel.
I can't help but wonder, shouldn't I be using a new, lighter Spring for the 9mm Barrel and Round? Also, can I shoot +p rounds with this setup or should I play it safe and avoid those? That's probably more of an opinion question, but an educated opinion is what I am looking for.
My most important question is with the Spring. Do I use the Stock 40cal. Spring with the new 9mm barrel and stock 9mm ammo. if I should get a new Spring, where do I get it please?
 
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