FYI S&W sells/sold a kit with both the 40 cal and 357sig barrels along with 3 mags. This is what I picker-up in 2010 it was an LE combo. The slide is marker 357 sig. but the 40 cal. barrel is in it the most! I also got the S&W 9mm and the proper 9mm mags never any FTE's etc. probably well over a thousand rounds through the combo's without a glitch. I am also probably over 600 rounds with the guiderod version of the lasermax and not one problem using all three barrels...