.40-9mm conversion

[silver78]

Not sure how the math works out now but a couple of years ago I traded my 1.0 40 in for a 2.0 9. I just decided to move out of the 40 and at the time there was a factory special on 2.0 9s.

 

[Formula55]

I found a Kkm barrel conversion around 200.00. What I was thinking though was I found an original 9mm slide, barrel and recoil rod and spring with 500 rounds on eBay. Starting bid at 175.00 with a day left. Of course it might go for more but thought this would be easiest. Thinking back I now remember how bad the trigger was. I didnt want to spend alot so I polished the trigger bar and bought the plunger from apex and that was it I think and it still has a long reset but its a non gritty , crisp 4.5# break. Not sure if it's the same plunger so I can move mine over and have the same trigger. If I get it for opening bid it felt like my cheapest way to go. If I put to much in it Im getting a new gun.

I just bought a rem-sport 9mm barrel for my MP 40 Shield 40. I noticed that top of the barrel where 9mm is stamped does not slope as steeply to the breach as the 40 does. The company assures they are interchangeable. Any input?

 

[Formula55]

An OEM 9mm barrel will fit and function in a .40 slide (assuming the correct length). The fit at the hood will be a bit looser which may affect accuracy.

View attachment 732393

A conversion barrel barrel will have the correct hood width.

You should get 9mm mags an perhaps a new recoil spring assembly (at least have a spare).

If this is to become "just another range toy", then an OEM 9mm barrel and mag should do it.

If you intend to use it for home/self defense, you should consider the conversion barrel.

If you want to add an optic, you could look for the 1.0 CORE slides (4.25" or 5") in 9mm. I put a Ported 5" CORE kit on my full size 1.0, then topped with a RMR.

I know this is an older thread. However I recently got my MP Shield 40. Yesterday 5/

An OEM 9mm barrel will fit and function in a .40 slide (assuming the correct length). The fit at the hood will be a bit looser which may affect accuracy.

View attachment 732393

A conversion barrel barrel will have the correct hood width.

You should get 9mm mags an perhaps a new recoil spring assembly (at least have a spare).

If this is to become "just another range toy", then an OEM 9mm barrel and mag should do it.

If you intend to use it for home/self defense, you should consider the conversion barrel.

If you want to add an optic, you could look for the 1.0 CORE slides (4.25" or 5") in 9mm. I put a Ported 5" CORE kit on my full size 1.0, then topped with a RMR.

I know this has been addressed but the MP shield 40 is new. I got my 9mm barrel from REM Sport. Looks fine. I put 50 rounds through it w/o cycling issues. I was however shooting left and down. I adjusted my trigger pull and grip and was able to center my shots Actually I didn’t have to work so hard with the 40 cal. Yes the slide gets easier to pull

 

[toddstang]

It was all S&W pistols Friday at my range.
The M&P 40c with the 9mm factory barrel ran flawless as usual.
Accuracy was spot on with 124 and 115 gr.

 

[JohnMcD348]

I did all of this when I bought my 1st M&P. It was a police trade in from Brinks Armored car service. Between folks here and a lot of Ebay Shopping, I was able to get a conversion barrel. Don't just get a 9mm M&P barrel and drop it in the slide. The .40S&W and .357 SIG barrels have a larger outside Diameter than what the 9mm Barrel has. In fact, you can buy a .357Sig barrel and it IS a drop in replacement in a 40slide. That's the whole reason for the need for an actual Conversion barrel. You can go from 40/357 to 9, but you cant use a 9mm pistol and slide and go up to the 40/357 because the barrel wont fit in the slide opening. there are other back and forth issues that get discussed about the actual recoil springs that should be placed in them when making the conversions.

I got the conversion barrel and it functioned perfect with 124gr 9mm ball and still using the original 40S&W recoil spring pack.

I also, got a few M&P1 lowers that came up for sale a few years back and got some of them becuase I ended up buying so many parts for my original M&P that I bought that I had enough spare parts to build 3 other full pistols. So I built one as a .357Sig pistol and 2 9mm Pistols. The sldies and internals are all interchangable on the M&P1's. I can take the slide off my original Brinks 40S&W and put it on any of the other 3 M&P1 frames and load it and shoot. You can't really do it between the M&P1 and M&P2 frames. There's slight variations between the two models.

 

[Formula55]

I previously mentioned I bought the Remsport 9mm barrel for my mp 40 shield. My first few outings with the 40 were fun and accurate at 15ft. Using the 9mm barrel was consistently low and left of center. To day I took both barrels and switched them after about 25 rounds. I was able to move my 9mm group right and just below center. Proving it was user error after all, as usual. That some how allowed me to move the 40 cal group right of center