Sounds like the firing pin(s) is/are dragging on the primer(s) which will cause the action to be difficult to open and can bend or break the firing pins.

Check to see if there are drag marks on the fired primers.

If there are drag marks check to see if they move freely or if they stick when protruding through the firing pin hole.

If they stick they could be bent or the firing pins could just need cleaning.

If the gun has been dry fired (this is one that you would not want to DF) it could have enlarged the firing pin bodies which will make them drag inside the recesses.