I have been experiencing jamming issues intermittently. Will shoot fine for maybe 20 or so rounds and then I get a audible click. Hammer has dropped and nothing happens. Bolt will not go back and live round in chamber. I have to manually pull back the hammer with screwdriver etc.. and drop hammer to fire off round. Bolt stll jammed and will not pull back with empty casing stuck in chamber. I have to hit bolt handle back with rubber mallet to eject casing. This as happened on two occasions and Ruger did nothing to the gun when I returned it for them to look at. Any Advise?