It wasn't until a few days ago that I stumbled on the info that some M&P 40 owners buy a 9mm barrel and use it in the M&P slide and use the 9mm magazines to avoid some feed failures.

I happen to own both the M&P9 FS and the M&P40 FS and today tried this without firing the pistols. I seem to be able to interchange the barrels and not only put the 9mm barrel into the 40 but the 40 barrel into the 9mm. Thank god the barrels are etched with size or no doubt I would have mixed them up---BUT---I have a few questions concerning

1. Are the recoil springs the same, or will not keeping the correct spring with the correct barrel present problems.???

2. If many seem to have had success shooting the 9mm barrel in the 40 frame and slide---has anyone had success doing the opposite--that is converting a 9mm frame and slide into a 40 by using a 40cal barrel???/

I really don't plan to play around with switchy changey as I would think that even the slightest difference that occurs when you switch out barrels could cause the pistol not to be as accurate as with its original equipment-------but----might be good to know in a pinch.

I don't plan to be the first to try shooting a 40 barrel in my 9mm because I really like having two hands and, as ugly as it is, the natural contours and shape of my face that might be affected when I attempt to fire the pistol the first time. Anyone who has actually used a 40 barrel in a 9mm PLEASE ADVISE------or if anyone knows the deceased pleasetell me where to send flowers.

I would be surprised if you didn't have to change the recoil springs. They are usually weighted to the round.

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Freedom isn't free.

Well, you can't shoot .40 cal in the 9mm even with the 9mm barrel because the breech face on the 9mm won't accept the larger .40 rim. With regards to shooting the 9mm in the 40 using a barrel and magazine swap, I have fired literaly thousands of rounds of 9mm without a single failure that I can recall. As far as accuracy goes I have noting to compare to since i don't actually have an M&P9 but, I can consistantly keep a 2" group at a measured 50 ft. I used the factory recoil spring for a long time but then went to a 19lb spring just to make it easier to find my brass. If I recall correctly the recoil spring for the 9mm and the .40 are the same part number. If you didn't want to use the factory 9mm barrel for the conversion you can get one of the "conversion" barrels for about twice as much and it will do a comparable job (as long as it fits as apparantly not all do without some work).

You sir are a hell of a shot! Have you considered trying out for the Olympic team?

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Freedom isn't free.

My 40-9 conversion barrel works fine with the factory recoil spring assembly. It is the same for 9 and 40.

Just ordered a 9 barrel for my 40, now if I can only find some magazines for the 9's.

Im looking myself, if I find anything Ill let you know.

Rastoff, I had not actually considered trying out for the olympic team. Do they have an event where you sit on the ground leaning back against the bumper of your truck and support the pistol with your knees. Actually pretty darn stable. Shooting offhand my groups are much closer to 4" with an occasional flyer at that same distance. But that's my shooting and should not be blamed on the pistol.

OK, my comment was somewhat tongue in cheek, but also serious. If you can hold a 2" group with an M&P pistol, then you're a better shot than most of the people I know; even supported. Change that to a 6" revolver from a rest and I'm not so impressed.

Still, you have what it takes. You should look into it. You never know, you could be the next gold medalist.

I hear a lot of claims when it comes to shooting. Most of them cannot be backed up at the range. If you're not one of them, I really think you should look into Olympic shooting. A 2" group at 15 meters with an off the shelf semi-automatic pistol is good shooting.

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Freedom isn't free.

I keep a two inch group also......two inch from this hole, two inch to the next hole, two inch to the next hole......

bmyers,
Well, you're better than me! lol

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Freedom isn't free.