I have a Bowen Redhawk Alpine Conversion that was made before Ruger offered the Redhawk in .45 Colt or with a 4" barrel. After years of solid use and excellent service mine developed the above mentioned problem wherein the gun would not fire when the trigger was pulled very slowly double action. To make a long story short, I shipped the gun back to Bowen and at first he could not figure out the problem. He told me he had never seen this happen before and it was very perplexing. Finally a Ruger engineer confessed to him during a golf game that Bill Ruger had felt that there was a very, very small chance that a Redhawk could accidentally discharge when dropped so Bill then quietly had the transfer bar redesigned. As a result, new transfer bars will probably not work in older Redhawks. It took a while to fix mine and shortly thereafter another expensive custom Redhawk was returned to his shop with the same problem. I asked him if he had any plans to make his own custom transfer bars (like he makes firing pins) and he said "No, the factory should just make them right the first time."
If you have a hard use Redhawk, you need to be aware that this can happen. Also, buy a couple of spare hammer links. I'm on my third one, as they do break at regular intervals.
Dave Sinko