Deaf: the Model 29 (29-1?) and 29-2 had the recessed chambers. They stopped recessing the chambers and pinning the barrels with the 29-3.
The 629 (stainless) came out after S&W had stopped recessing the cylinders (I believe).
leverfan is right Deaf, if it's a gas checked bullet it ain't onna Elmer's however, it may be a 'Keith Style' with a gascheck. And, 19 gr of 2400 is an easy shooting load for that revolver. I have used 20 gn of 2400 in my 29-2 and that's also a nice load to shoot. Both loads will do whatever you ask of them.
Sounds like a real nice Smith, Deaf. (LOL). Mikey.