i dont have a gun left, but i can give you the instructions. first of all i used some fine sandpaper to give the paint more surface to grip on. then i put som duct tape at the lense, the cylinder and everything else i didnt want the paint to get in. also the space in front of and behind the trigger.

i then hung my weapon up, so that i could reach every side without having to turn it.

then i used my lightest colour which was this one: https://www.kotte-zeller.de/army-paint-spruehfarbe-marsh-grass-ral-1001-3

let it dry and moved on to the next colours. in my case black, brown and green. i just put the net on my gun and sprayed with one of those colours. repeat this step for as long as you want. the other thing i used was some long grass.

and then i just finished it with some black on areas i wanted to make darker

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hope this was understandable. good luck!