M&P 9c to 40c conversion

[nurkvinny]

I've been reading how damned easy it is to make a 40c shoot 9mm... throw in a 9mm barrel and 9mm mags. Presto. (Disclaimer: research this yourself before doing it; if you do this and blow your hand off, don't blame me )

 

Also read that the reverse is not true. 9's can fit through holes made for the 40, not so the other way around.

 

I'd like to find out what is involved in making my 9c fire 40's. Any good links or insight?

If I had known how easy the 40-t0-9 swap was a month ago, I would have obviously grabbed the 40 instead. $70 for a 40 barrel and a 40 mag for a few bucks, you have a "second" gun in 40 for $110ish.

 

EDIT - guess not.

 

"The reason such a conversion is not practical is because the breech face required by the head of the cartridge is of different dimensions, with the .40 S&W having the larger dimensions. This is why it is possible to go from the larger cartridge to the smaller with maybe only a barrel change, but even that is not advisable due to differences in the breech face, which would negatively affect the grip the extractor has on the cartridge rim, and placement of the ejector, which will be in the wrong place, rendering ejection more problematic. Although people do it, it is not a good idea, and definitely such a conversion should NOT be relied on for serious work such as self-defense. The only one of these conversions that seems to work is .40 to .357 SIG, and that is because the cartridges have the same head dimensions and therefore use the same breech face. In the SIG and S&W brands, magazines are interchangeable between .40 and .357 SIG, but NOT in Glock, as Glock has found that a minor change is required in the magazines for the two calibers to get utmost reliability."

[RedRocket1647545505]

Most likely a new slide is required. I'm not 100% sure about m&ps, but on glocks the outside barrel diameter is larger on. 40, which makes a new slide a requirement. Unless you are ballsy and drill it out or something.

[Bam]

What about this....found it awhile back and thought it was interesting.

 

http://www.storm-lake.com/products/barrel#top

 

If you click through the drop down menus it allows you to select 9mm conversion for 40/357......this is an aftermarket/threaded barrel but what says you?

 

I also liked the thought of having 'two guns in one' and since I already have an m&p 40c this barrel and mags would allow me to have 9mm as well as add a suppressor if I'd like.

 

Not a good idea?

[RedRocket1647545505]

Swapping calibers is fine. To do it properly, you should change the barrel, mags, extractor and ejector (though the stock ones will usually work for both), and possibly the recoil spring.