I don't think it could hurt
I don't think it could hurt. I don't think it could help, either.
I suspect it would be like trying to use a wool sweater as sandpaper. A LOT of run time with VERY little result. Sawdust is not very abrasive. However, I would absorb a lot of whatever is on the outside of your brass.
Try it. Sawdust is cheap - free at any home depot or sawmill. Just show up with a a gallon freezer bag and a whisk broom. Ask one of the sales guys and I am sure they would think "Great, less that I have to sweep up".
I think it is an idea without merit. However, the world is full of "ideas without merit" that turned out to make fools of the nay-sayers. Maybe I should delete this paragraph so I don't have to eat it later.
Let us know how it works. I'll have my spoon ready.
Lost Sheep