Oh brother! I went to Edmond Academy today to take a look at the S&W M&P 40. They had one in the case. I discussed the option to interchange the 40 barrel to 9mm with the counter guy and he said that it can't be done due to magazine issues! Any comment on that?
I also looked at the Sig Sauer Model 250 40 caliber which also offers interchangeable barrels. We even swapped 9mm magazines into the Model 250 40 caliber. The Sig mag sure seemed to fit...
LL
Most Sporting goods store help is not the best place for info.
The 40/357 mags work fine with the 9mm ammo, I shot a bunch of 9mm with mine.
The only issue is that sometimes the last round stays in the mag and the slide stays open like it normally would when the mag is empty.
The 40/357 mags hold two extra rounds of 9mm, so I never had an issue with it.
If it concerns you, the solution is to get a couple of 9mm mags to use.
IMHO you will be much happier with the M&P over the P250. I have owned both.