Great find, I got one from my father just last year. Nickel plated with the 4' barrel. This is one of the most accurate guns I've ever seen. I love collectible guns, but I have this problem with owning a gun I can't shoot.
In my case my father purchased this gun for $50 back in 79 as my parents traveled by car a lot with my brother and myself shorly after. My old man has become absolutly against handguns in the past 5 years so I put my claim on it. I had no idea it was worth a good deal then, and it had less than 100 rounds through it then. It's still in 80+% although I've got over 1500 rounds in it now. It has a great trigger pull and has never failed to fire anything I've put in it so far. I shoot mostly Remington.38+P and it shows zero wear from shooting the +P loads. Called Colt and they said to me that +P is safe in any of the snake gun(python, diamondback) series.
Congrats on a terrific find.you will be hard pressed to find something that is more fun to shoot once you get the sights ranged in. The link worked (the copy quality wasn't very good however).
Colt Diamondback Serial #
I think I'll contact Colt and see if I can get an original from them just to have on hand. Yes it is somewhat of a collectible but I do plan on shooting it also. I take very good care of my guns (clean after every range trip using my version of Ed's Red).
I did a good cleaning and inspection of the gun (like I do before I shoot any gun, new or used) and like I said; mechanically it is 100%. I'm planning a motorcycle camping trip to my place in the woods this weekend, now I have to make sure I have room for my new addition. Easiest way is to check the serial number and compare to the approx Colt dates of manufacture. I'm not aware of any changes in the Diamondback design relative to handling higher pressure loads from its inception in 1966 to the time they quite making them in 1986. There were no design changes. I believe the 1972 date is just when Colt tested the gun with the ammunition.
1972 Diamondback serial numbers started with D51400; any other prefix will be a later production gun. The 'D' prefix ended in 1976.