Well I bought a Gamo Swarm Maxxim in .22 caliber. I watched a lot of videos on You Tube. One thing that I could not understand is why it takes so much cleaning of the new barrel. They tell you to use at least 20 patches to get the junk from the factory cleaned out. I have been cleaning my guns including my AR with non-chlorinated brake cleaner for many years with great results. What I did with my Gamo Swarm Maxxim was to cock the barrel down and left the action open so I could look down the bore. I was VERY careful to spray the brake cleaner down the barrel while pointing it down so I would not get any of it on the gaskets in the piston parts. I put a clean white paper towel under the barrel so I could see what came out with the brake cleaner. A lot of junk came out onto the white towel. Then I pushed a new bore mop down the barrel. It came out pretty clean. Then I pushed two new patches through and they came out perfectly clean. WALAH it was done. I then closed the barrel with a pellet loaded and shot it into the ground while pointing it down. Then I leaned the rifle with the barrel down over night to be sire that none of the brake cleaner would drain back into the piston parts. This morning I ran another patch through it and it came out perfectly clean and dry. Very easy compared to the instructions on You Tube.
