Hi. Greetings from PR. I adquired a Blackhawk in .45 Colt, brand new, same problem. The problem was the base pin. I will explain. It had way too much endplay, moving back and foward. Plus, the tip at the end, that is spring loaded, that actually pushes the transfer bar out of the way, looked kinda short. Also spring tension was weak. Add all that and the gun wont cock. The transfer bar will not clear the firing pin, thus not allowing to cock.
Solution. I got a replacement part, better than oem, at ebay:
Power Custom/Grandmaster® Base Pin Keith #5 Ruger Single Action 2.875" Blue (Q1-01).
LOok for this and find the stainlees version you need (Q1-02).
It solved the problem completly. Best part is it comes with an allen tool to lightly thighten the base pin in position, so no more endplay!
Hope this helps you. Kind regards.
Locking pins have an allen set screw in the head to hold the pin in place against recoil. Installation instructions are included and on most guns these pins drop right in. You can use the New Blackhawk (longest) and shorten to length.
www.ebay.com