BTW Smith & Wesson did make a 9mm Centennial Airweight the Model 942 but only "ONE" was ever made "By Them" & several others have been converted via cylinder reaming & cutting for moon clips & some have fit 940 cylinders to their Airweights..
I fit a 940-1 cylinder to my 642 No Dash & did so by filing the ratchet & set the end shake via Power Custom end shake shims so that the cylinder can be convertible into the 38spl Airweight..
The 9mm works very nice in this platform but some have extraction problems mostly due to rough cylinder bores that usualy can be fixed with Brownells Flex Hones which I have a set of in 9mm/38spl/357mag, I have loaned these to several forum members with great success..
Here's a few pics of the 642/942 Convertible & one of my 940 which wears the Smooth BTS Spegels..
The Airweight has the checkered grips..
Gary/Hk

9mm S&W Snubbies