The Colt Single Action Army revolver with the serial number SA31171 was manufactured in 1974. The Colt Single Action Army, also known as the Colt .45, has been produced in various years since its introduction in 1873, but this specific serial number indicates a production date in the mid-1970s.
about 1976
Around 1885.
about 1875
A Colt single action 1860 army with that serial number was made in 1866.
Your colt single action army dates to 1881 with the serial number you provided.
The Colt Single Action Army revolver with serial number S14162A was manufactured in 1976. Colt's serial number system indicates that this particular model falls within that production year. For precise information, it's often best to consult Colt's archives or a dedicated firearms historian.
If it is Colt single action army, then it was made in 1889.
eBay
probably made early 1980's
If this is a Colt single action army, it was made in 1874.
Look on the frame
My records indicate that your 45 colt single action army was made in 1883.