# S&W M&P 40s' EASY CONVERSION TO 9MM



## robkarrob

Just a little information. All M&P pistols in 40S&W will allow the swap to the 9mm barrel. I doubt it was engineered by S&W to be a drop in barrel swap, but more likely just done to make manufacturing easier and less expensive. The 9mm and 40 basically use the same slide and barrel dimensions. S&W states it doesn't work and should not be tried. However there are thousands of M&P owners that have used this barrel swap, and I have never read of a single issue with the barrel swap. People often ask which is better the 9mm or 40? If you own a M&P, the answer should be to buy the 40, and then purchase the 9mm barrel, and you have two calibers in one gun. The swap is size related, so if you have a full size, then a full size barrel, etc. I own the 40 Shield and was able to purchase a stock Shield 9mm barrel ($70). I can be at the range shooting 40 ammo, pull the slide, pull the 40 barrel and put in the 9mm barrel, replace the slide and start shooting 9mm ammo. On the M&P models, the extractors, ejectors, and recoil springs are the same between the 9mm and 40s. I also found my 40 mags allow perfect feeding of the 9mm cartridge, but others have had feeding issues on the last round in the mag, when using the 40 mags to feed 9mm ammo. It is a feed lip width issue with some of the mags. I did purchase a few 9mm mags, which also work perfectly. At 15 yards the groupings are identical in size, however I found the 9mm to impact 2 inches right and 2 inches lower than the 40's impact point, with the same point of aim.

This only works 40 to 9mm, and does not work 9mm to 40, as the upper rear barrel tang width is slightly wider on the 40 barrel, and will not fit into the narrower tang slot in the 9mm slide. I use my Shield as a 40 for SD carry, but shoot a lot of 9mm ammo, at the range. Cheaper and less recoil/flip. The major issue is finding the 9mm barrels, as they are scarce, and in big demand. I don't know if any other brands allow this easy barrel swap, but it works great for S&W M&P 40 owners.

Bob


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## youngvet24

Cool advice


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## SouthernBoy

I solved that concern a few years back. I ordered an M&P 9 Pro Series 4.25" barrel and shoot the heck out of it. My first M&P purchase was my M&P 40 4.25". Since added the 9 Pro, I have purchased an M&P 45 4" barrel, an M&P 22 (you gotta get this one), and an M&P 9c. These are all great guns. All but the M&P 22 have had work performed by me or an armorer to make them great shooters.... which they are.


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## EEBigdog

Hi Bob,

Unfortunately, this conversion is no
longer "easy".

S&W will no longer sell just the 9mm
Shield barrel.

Grant


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## GCBHM

SouthernBoy said:


> I solved that concern a few years back. I ordered an M&P 9 Pro Series 4.25" barrel and shoot the heck out of it. My first M&P purchase was my M&P 40 4.25". Since added the 9 Pro, I have purchased an M&P 45 4" barrel, an M&P 22 (you gotta get this one), and an M&P 9c. These are all great guns. All but the M&P 22 have had work performed by me or an armorer to make them great shooters.... which they are.


So am I understanding you correctly in that you swap barrels, and you have had no issues with doing so?


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## Reyniak

GCBHM said:


> So am I understanding you correctly in that you swap barrels, and you have had no issues with doing so?


I have an M&P40c. I bought a S&W factory 9mm compact barrel (and mags) and a Storm Lake .357Sig compact stainless barrel from Midway. I have put literally 1000s of rounds of 9mm (all types, reloads, steel, everything) with no problems. I have a few hundred rounds of .357Sig through it and no problems.

.40/.357Sig mags will feed 9mm, but not reliably. I couldn't find any factory 9mm mags when I bought the 9mm barrel, so I had to get ProMags. Never had any problems with the 9mm ProMags.

Regards,

Rey


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## robkarrob

Yes this swap works great, and all you need to do is swap out the barrels. No worry about recoil springs, extractors, ejectors, etc., as the 9mm and 40 M&P pistols use the same parts. The only issue right now is it is hard to obtain the stock S&W 9mm barrels. There are several aftermarket companies making the conversion barrels for the Full Size and Compact models, but none for the Shields, so a stock barrel is the only option for the Shield. The issue with the aftermarket barrels is they are about double the cost of the stock barrels. Now that gun sales are starting to decline, possibly in the future S&W may release the barrels for resale through distributors like Brownells and Midway USA, like they did in the past. I got my stock 9mm Shield barrel back at the end of 2012. S&W was then allowing a small quantity of barrels to be sold to the distributors, for resale. A few months later they stopped selling the barrels to the distributors, but back then the a number of S&W's models were sold out for almost a year in advance. Now the gun magazines and blogs are writing that gun sales have come to a near complete halt, except for a few "HOT" gun models. So time will tell if the barrels become available again.

Bob


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## O23fish

Hey, the G23 will do the same, .40 to .357 no problem, same mags ect. Never tried 9mm but may work as well. Nice having two calibers in one set up. FYI...have fun


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## gmurf

*Where?*

Bob

"I own the 40 Shield and was able to purchase a stock Shield 9mm barrel ($70). " Do you know where I can buy a 9mm barrel for the shield?

Thanks in advance.


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