Light machine gun or submachine gun? If it's an LMG (Bren) it could be worth up to about £800 in good nick, deactivated. An SMG (Sten) would be hundreds of pounds, too. (I'm assuming it's from the 1940s.) Go find a spade!
You could grind the rust down to the metal in some places, but never properly restore it, sadly.![]()
I don't want to go into too much detail, public forum and all that jazz but drop me an email to my trust if you want to know a bit more

Yeah I meant just cleaning it up a bit more really, I kind of like that it's gnarled and pitted though
