Anyone ever do this and what's the technique? Does it damage the pans levers etc?

I do this with my MB 650’s whenever I get a batch that is in need . I use sand blasting media #50 and a couple coffee cans full of 3/8” gravel . 4 to 6 at a time is plenty with chains on as they get tangled pretty good. This does a very good job and the traps only need an air hose before they are dyed and waxed .

PS. I use the stuff called Black beauty.

^^ yep coal slag ^^
Pea gravel also works.

Thank you.

For what it’s worth, I did 4 doz badly rusted #3’s 20 years ago in pea gravel for the MSU Dioxin Great Blue Heron Prj. I didn’t like the outcome but I admit to being pretty particular to what happens to traps I use.

x 2 on the media blast. Do yourself a favor and remove the chains if it has paddles still in the mixer.

That's the right answer

Chicken grit - nice and sharp and hard.