Colt diamondback, 6”, 22lr, $5,000
!!!!!!!! That one had better have had fancy engraving, gold inlay, and a famous person's provenance.
There is a 50/50 chance it has a bad barrel. It took me 43 years to get mine to shoot and it's only because I found a new barrel to put on it. I bought mine in 1978 and left it in the gun safe for 22 years unfired. About 20 years ago I went to shoot it before giving it to my son. It shot a 6" pattern at 25 yards. By this time Colt had gotten out of the revolver business and had no one to look at it. I sent it to one guy in Arizona and he charged me $150 to get some lead out of the barrel and chamfer the muzzle. It slightly improved the barrel but not by much. I was still getting 6" groups at 25 yards. I finally found a barrel and took it to Cylinder and Slide in Nebraska and they put the barrel on the gun. It still shoots poorly but now the groups are 2" at 25 yards.
I had a friend who bought one at the same time I did in 1978 and he shot it right away. His shot the 6" groups as well. He sent it back to Colt and they told him the throat was cut wrong. My guess is he got a new barrel but they never told him that. Lesson learned. Just because it says Colt on it doesn't mean it's going to shoot good. Especially if it's from the 1970's. I would never pay anywhere close to $5000 for a Colt .22 Diamondback knowing what I know now.
kwg
