Question can't be answered without knowing the caliber.
By the serial number.
IF YOU CAN REMOVE THE HANDLE THE SERIAL NUMBER SHOULD BE THERE. YOU CAN TAKE THE GUN TO YOUR LOCAL POLICE DEPARTMENT AND HAVE THE GUN REGISTERED OR SEE IF THEY HAVE A PROGRAM WERE THEY BUY THE GUN.
The primary serial # is stamped on the barrel of the gun opposite the cartrige ejection port
You will have to call S&W
Could be a Military and Police.
If you call SW and give them the serial # they can tell you.
Contact S&W and ask for a historical letter.
a serial number for a model 29 sw is 72-486
No serial number provided.
Need more information, including any other markings on the gun.
It will be marked on the barrel.
Since the first one was made.