I purchased a FS 40 a couple years ago, and am currently running a 9L slide assembly on it. I change it back to the 40 from time to time, and never have had any problems with either setup.
Found the same thing to be true. Took it out for a test and it did wonderful. The 9mm is a better caliber for USPSA production because it is cheaper. I have loaded down the 40 S&W to 140 power factor with a 140 grain lead TC and it is a very easy loading to handle. But a 147 grain lead TC in 9mm does well and is cheaper.
Sounds like you answered your own question. I would have said that the 9mm M&P was derived from the 40. That is why the 9mm mags fit the 40 frame which allows for a 9mm conversion barrel to be used. Changing the slides between each would work as well. I've seen members say that they merely have changed out the oem barrels & shot 9mm from a 40s&w gun. I can't confirm that. I went to the gunshop and asked them to try it. They did while I was standing there, but the slide would get jambed because the barrel wouldn't return to wherer it was supposed to be. Don't know...
Ah, the joys of 9mm and 40 conversions. btw, on a semi-auto pistol the lower portion is called the "frame", not lower receiver. That's AR nomenclature.
Right. I remember I couldn't think of the term. I was in a hurry with the thread hoping to get an opinion before I went to the range. In fact I was thinking that I haven't shot my AR15 for over a year. Probably where I came up with receiver.
Can you switch lowers?
They fit. But could I have trouble?
Found the same thing to be true. Took it out for a test and it did wonderful. 
The 9mm is a better caliber for USPSA production because it is cheaper. 
I have loaded down the 40 S&W to 140 power factor with a 140 grain lead TC and it is a very easy loading to handle. But a 147 grain lead TC in 9mm does well and is cheaper. 
Linear Mode
