M&P Conversion

[blacklab11]

Is it safe to convert a full size M&P .357 Sig or .40 S&W over to a 9mm??????

 

[RobzGuns]

Is it safe to convert a full size M&P .357 Sig or .40 S&W over to a 9mm??????

Depends on if you're talking about just using a S&W Factory 9mm Barrel, or an Aftermarket conversion barrel.

Some are comfortable with just buying a Factory 9mm barrel in their .40, or .357, while others aren't comfortable with the dimensions differences and would prefer buying one of the various Aftermarket barrels specifically made (and compatible) with the 9mm slide.

 

[WA101]

I shoot 9mm in my M&P 40 all the time using a factory M&P 9mm barrel and magazine. I've never had a problem with this set-up.

See the link below for more details on the M&P 40 to 9mm conversion...

http://www.ar15.com/forums/t_5_16/1...photo_comparison_UPDATE_IN_OP_Range_test.html


Sent from my iPad using Tapatalk

 

[robkarrob]

Yes I also use a stock 9mm barrel in my 40. There is a slight bit of extra side to side play, at the rear of the barrel, when using the 9mm barrel. This is the only area where the barrels differ, other than the bore diameter. I have highly accurate measuring devices (calipers, micrometers, dial gauges), and the only difference between the barrels is that the 9mm barrel tang width, at the top rear of the barrel, is slightly more narrow than the tang width of the 40 barrels. This allows a maximum of 12 thousands of an inch (equivalent to 3 sheets of paper), extra side to side play at the rear. This is very minimal play, and the 9mm barrels seem to self center, eliminating the play. This extra side to side play causes no issues in the gun's operation or accuracy. My shooting groups, when swapping barrels, are both under three inch groups, using one handed shooting at 15 yards.

You will always get people stating they would not trust using the stock 9mm barrels in their 40s. I would not try to try to change anyone's opinion, but myself and hundreds of others have been using the stock 9mm barrels in their 40s, for a long time, with no issues. If there was a problem, this Forum would be filled with negative threads and posts, but I have yet to find any that said the 40 to 9mm barrel swap did not work perfectly, and I have been a member of this Forum for over two years.

Bob

 

[blacklab11]

I want to use a factory 9mm barrel from S&W. Thanks for the replies.

 

[blacklab11]

How about the recoil spring, must it be changed?????

 

[robkarrob]

No nothing needs to be changed. Just swap the barrels and shoot. I can use my 40 mags to feed the 9mm cartridges, and they feed perfectly. However some have indicated jams when using the 40 mags to feed the 9mm rounds, especially the last round in the mag. I did buy some 9mm mags, but found I did not get any jams, using the 40 mags. So just buy some 9mm mags, and you will not have any issues. 9mm mags are designed to feed the slightly more narrow diameter 9mm cartridges. I just happen to be lucky, as my 40 mags feed the 9mm rounds fine.

Bob

 

[VitalStatistic]

Ordered a factory S&W 9mm barrel and 2 mags from G&R Tactical for $149 + shipping. Got them in 3 days - great service. Barrel drops right in, and the mags fit perfectly. Going to shoot it tonight or tomorrow when I get a chance to get to the range, but based on the fit and ease of cycling, don't expect any big issues. Will report back.

 

[MikeV]

I've used a S&W 9mm barrel from Brownells in my M&P 40 for about 400 rounds with no issues. I bought a 9mm magazine just for the conversion but hadn't tried the .40 mags as previously mentioned. I'll have to give that a try.

I've been considering a true conversion barrel just based on the tolerance aspect and the potential issues that could, but haven't, arise. It's more money than I want to spend on it at this point, so it's good to hear some positive feedback on my current setup in threads like this.