Hi folks, new boy here. I need some help finding a manual for the complete disassembly of a Beretta "Lightning" clone. (please don't laugh, I grew up shooting a pump .22 and spent 35 years of my life shooting pump shotguns...just had to have one

) Berretta is absolutely no help and I would like to at least be able to take the gun apart to completely clean it every now and then. The gun already had to be returned to the factory for something I probably could have fixed so I would really like to have a good manual.
Any help would be greatly appreciated.
Rob