I have a Model 60 and after about 20 rounds the double action trigger pull becomes extremely heavy, as if it was binding. It does not do this when the gun is cold.

I cleaned the gun and it did not resolve the problem. The ejector rod appears to be a little out of round but I do not know if it is enough to bind the cylinder. Any thoughts on this and would the gun heat up enough to induce the problem?

Thanks for any help. I am always impressed with the knowledge and experience on this forum.