Countryboy,
If it's an S&W revolver, and the model number starts with a 6, it is stainless steel.
Unfortunatly this doesn't work quite as well for the S&W autos, especially the 3rd generation ones.
The 645 (2nd gen.), yep that works.
But the 3rd gen. equiv. is the 4506.
Elmo,
If you like the underlug, and it works for you, GREAT! Please don't feel insulted or belittled by my comments. I know a lot of people who prefer the full-underlug guns. I, however, don't, except on .44s with really hard kicking ammo. That's when the extra weight comes in handy.