Hi, does anyone know the SS alloy that Smith uses for their revolver frames?

I believe it is a 900 series, maybe 916.

900 series?, I figured it would be one of the 400 series, just trying to figure how weldable (tig) it is and a proper filler

What are planning on welding on it?

some mods in grip area

To be certain, you could locate a Metallurical lab that specializes in "Optical Emission Spectroscopy" and let them do an analysis of the frame. It's relatively simple, and can be done in an "out of the way" location on the frame and is relatively non destructive.

I say "relatively" because the area that is tested is exposed to Argon gas while a series of sparks are played over a the area to evaporate a small part of the surface which emits light (photons) and is recorded by an Optical Spectrometer, which, after calibration, provides an elemental analysis of the sample. The small test area has a slight frosted appearance which can easily be polished out or blended.

Maybe a call to Smith & Wesson?
Maybe Bowen Classic Arms could tell you?
They do a lot of that sort of thing.

Malm very informative info there , thank you

Yosam , I call S&W first as well they should have that info handy