I have a Ruger Bisley Vaquero that I have replaced the factory mainspring with a reduced tension spring and I also polished the hammer. The gun is now locking up after 3 or 4 shots. You can pull the hammer back about 1/2 an inch and then it won't move. If you help the cylinder rotate a little it will then function properly until you fire 3 or 4 more shots. Any thoughts? I thought that the pawl spring maybe holding to much tension against the pawl.