Disassemble completely and degrease
Acetone or simple green your choice
Clean and clean and then clean more
And when you think your degreased enough
I like to de gas the pieces in the oven for a bit before actual application
I like alumahyde from brownells or even duracoat in the can
But if your looking for the cheap
Krylon fusion works great on plastics and metals
Or a high heat engine paint works just as well
You can cure the parts in your oven after they dry
Then hang em for a week and forget about them
I forgot to add appliance epoxy paint works great as well
Here are a couple in camo. I tend to start with some kind of grill work or netting, then I go over that with a natural sponge that I’ve wet with paint. I think random, chaotic, and rather high contrast patterns do the best at breaking up outlines. But, it all depends upon your environment.
You can also buy some strong/thick elastic cordage and tie various colors of yarn to it. Then, wrap it around the rifle, being careful not to obscure your optic. I find that such three dimensional camo is really the most effective. Neutral color zip-ties can be used to attach actual foliage from your specific area quickly and easily.
I’ve had a couple factory painted guns, where they were handled and carried on sling that rubbed against my coveralls the paint wore off. I agree they look neat but I don’t have any wall hangers, cerakote and powdercoating is the way to go for long lasting color. granted it’s not as cheap, but if the paint rubs off in a short period of time it wasn’t worth the effort to make it look good. just my opinion with what I have seen.
Here’s one I did years ago with that Krylon Camo stuff. I’ve hauled this all over the place and hunted with it. It’s still holding up well. It’s subtle, but I like it. Used to have the barrel and action camouflaged too but decided to strip it back to the stainless and leave the stock.