Rock tumbler?
 

My question is can I use a rock tumbler to clean brass like a brass spin tumbler, without damaging the brass? The brass that will be cleaned is 40 S&W, 45 ACP, 30-06 SPR, and 30-30 Win.

Yes. Just use the proper media like walnut shell which is very cheap at pet stores.

I have been using a Thumbler's Tumbler for 35+ years for pistol and rifle brass. The media I use is Lyman Turbo Tumbler Media in Corncob Green. I cut a fabric softner sheet in four and the media lasts a long time with nice polished brass.

A rotary tumbler will polish just fine, it just takes longer than a vibratory one.

Picked up a little rotary tumbler, no container, at thrift shop, $2. Use a coffee can with snap on plastic lid, fill 1/3 full of brass and walnut shell media. Works well. Too much weight, will not turn. Plug it in in the shop, let run overnight.

That is what everyone had to use before the vibratory ones came on the market.

I bought mine at harbor freight about four months ago and its worked great for me. Ive cleaned probally 2000 pieces and its still going strong. I believe for the tumbler and the media it was a little over $50.

Thank you for all the great responses.

Your drive belt is probably stretched. I have found that the larger plumbers O-rings make good drive belts. mine uses a 3.5".

I use a Thumler's model B with warm water and Tide.

Much faster then regular media. (20 minutes)