tumbler finish

[woodie headed merganzer]

I was wondering if any one had tried to use a tumbler like you would polish ammo brass in to polish acrylic?
I tried it in my uncles tumbler for like 7 hours but very little differance. He said the grit he used is like crushed
corn cobb or something like that. I just thought it would have done a better job. Any suggestions on a different material
to tumble with?