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

[S&W-Admirer]

I have a new full-size M&P .40 S&W. I like the idea of having the option of two calibers in one pistol, so I bought a 40-9 conversion barrel from KKM Precision.

The conversion barrel did not work reliably with the .40 S&W magazines. The magazine wouldn't hold the 9mm rounds securely. Inserting the magazine was more difficult, cases ejected erratically and the slide wouldn't lock back after the last round.

I miraculously bought 2 new 9mm magazines at a reasonable price from a local individual. The conversion barrel works perfectly with 9mm magazines. Ejection of cases was consistent and out of the way.

It seems the M&P series is particularly well suited for a 40-9 conversion barrel since the extractor and ejector are the same for both calibers. The fit and finish of the KKM barrel is excellent. Easy drop in fit. Well worth the money. I'm pleased.

 

[timn8er]

Where did you find the KKM barrel?

Thanks!

 

[S&W-Admirer]

I ordered it direct from KKM Precision. Look under the .40 barrel options for 9mm conversion.

 

[Jyezahn]

FYI, you can just order a factory barrel from S&W for half the price of the KKM. Just drop it in, get a magazine or two when you can.

 

[Zjnovak]

I've heard of alot of people using the 40 S&W mags with the 9mm barrel. My experience is the same... bad feeding, ejecting, etc.

 

[MSG Glenn]

You very definitely need 9MM mags for a 9MM conversion of a .40 cal M&P. If you convert a .40 to .357sig you can use the same .40 cal mags. The same mags are used in M&P .40 cal & .357sig.

Some have used .40 cal mags with a 9MM conversion with mixed results. Use it only at the range & expect feed problems. Never use them for SD carry unless you have 9MM mags.

 

[S&W-Admirer]

I shot 25 rounds of factory 9mm through the KKM conversion barrel and 9mm magazines this weekend and had perfect reliability. I also like the way the stainless barrel looks in the all black pistol. I'm pleased with this purchase.

 

[eldridgebills]

Why conversion barrel?

Stupid question, but do you need a "conversion" barrel, like Storm Lake and KKM sell, or can you just get the 9mm OEM barrel (or 9mm barrel from Storm Lake and KKM and others) and slap it in? If so, why do they bother selling a conversion barrel? Thanks

 

[Jyezahn]

Just get the barrel directly from S&W. It's about half the cost. Others sell conversion barrels because they can.

 

[Bret]

How much does a barrel cost directly from S&W?

 

[Jyezahn]

M&P9 : Part #278430000 $79.20 X BARREL

M&P9c: Part #277850000 $77.46 X BARREL

 

[S&W-Admirer]

It may not matter much, but the 40-9 conversion barrel fits the M&P slide and breech face exactly. The factory barrel does not but is close enough. The conversion barrel may be more readily available for purchase as well. The M&P pistol is ideal for conversion since the 40 S&W and 9mm ejector and extractor are the same. Other pistols, like Glock, require a 40-9 conversion barrel to fit the slide.

 

[blacksheep515]

M&P9 : Part #278430000 $79.20 X BARREL

M&P9c: Part #277850000 $77.46 X BARREL

I tried searching for this p/n on the S&W site and I am coming up with nothing.

I have a S&W M&P .40 I just purchased and I am interested in having the 9mm conversion so I have the option to use it.

Sounds like all you need is a barrel and swap it out. Seems like the best option is to buy some 9mm catridges as well. No spring etc is not needed then?

Thanks all!

 

[Jyezahn]

I tried searching for this p/n on the S&W site and I am coming up with nothing.

I have a S&W M&P .40 I just purchased and I am interested in having the 9mm conversion so I have the option to use it.

Sounds like all you need is a barrel and swap it out. Seems like the best option is to buy some 9mm catridges as well. No spring etc is not needed then?

Thanks all!

Those are the right part numbers. They won't show up on the site because they don't sell them on the site. Call S&W to purchase.

Yes, barrel and magazines is all you need to swap out.

 

[blacksheep515]

Thanks, Jyezahn. I really appreciate the quick reply and education. I am a n00b, so this really helps!

 

[Jyezahn]

That's what this place is about, my friend.

 

[reckless1911]

perfect.. this thread has everything I need to confirm my next purchase will be a M&P 40 range kit.

**as soon as this stupid Maryland background check bag log starts to decrease from the current 60+ days, and before the October 1st high capacity (anything over 10) mag law kicks in.

 

[reckless1911]

does anyone have the part # for the .357 sig? im sure S&W will look at me funny when I call to order a 9mm and .357 barrel...lol

 

[Jyezahn]

This is for the M&P 357: part #277550000 $92.13 X BARREL

 

[K.macocker]

The 9mm oem barrel in my factory .40 has less wiggle than my .40 original barrel.

I'd like to purchase the .357 barrel. But I've yet to ever have seen .357 sig ammo ever! Where would I buy such?
Kmac