What brand of tumbler is it?

You need a dental pick or similar to remove the walnut. I don't bother with screws any more, too tedious.

The medium sounds right. Let it tumble for 48 hours.

I saw wet tumblers with ceramic media, would be very interested to know how they work.

You should have little difficulty in getting a great sheen on your metal parts using a tumbler, walnut shells (medium should be fine) and a good additive. I reckon Flitz Tumbler/Media additive available on Amazon is terrific. You need to remove any gunk/grease etc before putting in the tumbler.

No rinse just a quick hand polish if necessary with rag. I don't tumble screws. I find it easier just to use a rotary wire brush.

how long are you running it? as above .. 48 hours is a good guide..

yeah needs 2-3 .. keep at it

Flitz and medium grit walnut shells work great for me. 2-3 days depending on how bad the parts started.

That sounds odd. How much polish did you add?

I have used aquarium gravel on some of my parts.....works well. I usually put them in when I go to bed and take them out in the morning. Roughly 7 or 8 hours. I put in some water and a small amount of dish soap. Does a decent job in much shorter time. Also cheap, can get at Walmart, etc...

Recently I had to switch to corn media because of my son having a tree nut allergy, I was planning on being disappointed in the results of polishing but holy cow I was wrong. My metal parts appeared to come out better than what I have achieved with walnut shells! I use Novus 2 as my additive.

Brian

After you tumble you can put your screws in a 'baggie' and shake. That will remove quite a bit of the media out of the heads. I use to put all the washers on a pc. of wire(twist ends together)to keep them all together. I also used a magnet to search for the parts in the media. You can also sift. I used Flitz Polish and walnut media running for 24 hours at the most. If heavily rusted/dirty, as others mentioned cllean first. Ultrasonic cleaner works great for that. Enjoy the hobby.