It would help greatly if we knew what the word "cleaning" means in this instance. For me, the word cleaning includes the inside of the cylinder (operating rod) and the fixed piston to include the inside of the piston. It also includes a thorough bore cleaning.
!! VERIFY IT'S NOT LOADED AS STATED ABOVE !!
Verify that the bolt moves free. You can do this by inserting your fingers or a pencil (eraser end first) through the magazine well and pushing up and down. If the bolt acts as if it's part of the receiver, then it's the bolt. If it moves, wiggles, or acts as if it's being held by the slide, it's your piston. If it acts as if it's part of the slid, you might have something jammed or assembled wrong.
I'm also of the opininon that the piston is rusted to the operating rod. No really easy way of removing it. First, thoroughly soak the piston in some type of penetrating oil like Break-Free. Let it sit overnight like that. You can use a piece of 2x4 and a hammer placed against the part of the slide where your hand goes... and WHACK the wood with the hammer. This prevents marring the slide but should provide sufficient force to dislodge the slide.
If the bolt is stuck, I'd also soak it in Break-Free overnight. REVERIFY THERE IS NO ROUND IN THE CHAMBER!!! You must first try to rotate the bolt. If it is all the way forward, the left locking lug will be even with the lug recess and the bolt will appear flat. If it is this way and stuck, you can strike the left lug with a brass punch a few times and it might free it.
If the bolt has rotated but still won't go rearward, insert a metal rod (invest in a brass one to prevent marring bolt face) through the bore. Placing the butt of the rifle against carpet or some other non-marring flooring, apply pressure with a shoed foot against the operating rod. Gently tap on the end of the rod until the bolt is free. The reason for applying pressure to the slide is that you must rotate the bolt to open the action..
