I have a strange problem that only happens when live firing. When firing my 1959 cobra double action the cylinder will lock up almost every other shot. When I pull the trigger to fire a second shot the bolt drops and the cylinder rotates about 1/3 to 1/2 of its travel and then stops. The bolt is retracted and almost ready to pop back up but the cylinder is locked unless I help it rotate by hand. This problem cannot be replicated when dry firing with snap caps. Any help is appreciated. It almost feels like the cases are catching up on the recoil shield or something but after I've got it working again I can go back to that fired chamber and continue shooting double action from there.