my first look would be at the firing pin, opening that hard for me usually had pin stuck forward in "fire" position and good chance that the pin is bent. open action, unloaded of course, and use small screwdriver to push pin forward from hammer side. does it move easily and project thru breech face approx. 040, and then when released does it retract immediately back inside completely? bent pin or gummy pin/bore if it doesn't work easy both ways. have straightened pins a time or two, but it's a challenge. surest fix would be to replace pin, just make sure to get right diameter. problem could be elsewhere but pin is where i would look first. regards, jather...