I know some folks use a mix of these methods to deal with especially dirty brass or achieve a specific cleaning goal. In my research, each method seems to attack 1 or more brass cleaning 'problem' better than the others.
I bit the bullet and just bought an ultrasonic cleaner since the prices for them had come down. From everything I read and all the videos I saw, it seemed ultrasonic would suit 90% of my general brass cleaning needs-unless I want super shiny polished brass. Up til now, I have hand cleaned my brass, so this is a quantum leap in my reloading journey.
I do like JimP does. I use Lizard Litter for media. It is walnut shells that I get from a pet shop. I pay about $10 for a #40 sack...way cheaper than Lyman or other commercial media and does just as good a job.
I use ultrasonic only because I happened to have one. A decade ago I was rebuilding an engine as a hobby project and bought one of those huge units off eBay.
It works well but I don't like it, and if I get more into reloading enough to justify it, I'm definitely going to get a dry tumbler. Three reasons based on my experience with ultrasonic:
1. They take longer, in my unscientific, completely non-data-driven anecdotal opinion. It could be my cheap unit, but if I was going to fix it with a more expensive one, why not switch to a tumbler anyway?
2. You can't see what's going on as easily. Mine is a large 30L unit and it's nice because I know I can clean basically anything. But once that cleaning fluid gets even a little murky, it's a total swamp in there. To check the progress you have to dip in and pull out a case or two. Not a huge deal, but I feel like with tumblers something's always floating around the surface where you can get a glimpse.
3. You never know what to do with the dirty cleaning agents. Some are water-soluble, but they don't clean as well and I just don't feel right dumping them down the drain. Auto shops won't take it like they do with oil, they're hard to recycle at home (filter), and who wants to make a special dump trip with jugs to drop off in the hazmat? I could be just totally wrong on this, but I feel like the walnut shell litter is friendlier to dispose of and you do get a lot of use out of it...
I tried the ultrasonic method and I decided against it. It was just too much of pain in the butt and it corroded the cases and primer pockets with the concoctions I tried. It did clean the insides well though.
I just tumble mine with a harbor freight tumbler now with the cheapest media I can find. I can do a couple hundred at a time and as I shoot them I just toss them into the tumbler. (I never separate them by caliber when I tumble them, I do that when I pull them out)
Is I have a LOT of brass 1000+, I put them in my harbor freight cement mixer with scalding hot water and dawn dish soap.. That works well for quantity in my opinion a person should de-prime the cases first unless you have a fast way to dry them like an outside convection oven or something of that nature.
My 9mm longshot loads are pretty dirty so I normally save the hot water and dawn for them.
Keep in mind I am NOT a precision reloader for the 9mm. lol
Some of the powders I've been using seemed really dirty or I wasn't getting a full burn; hence the insides of my cases were getting really filthy. A good buddy uses a shaker with the dry walnut or corncob and it does OK, but doesn't get the insides real clean. I know some reloaders have shared that they like a little carbon buildup inside the case as they feel it helps hold the bullet. The ultrasonics and wet tumbling with the stainless steel pin systems are supposed to get the insides cleaner than just dry tumbling, but the dry tumbler is supposed to polish the outsides better. All these methods obviously clean the cases. The dry tumblers can kick up nasty dust, the ultrasonic and wet tumbling systems leave a nasty cocktail to deal with. Issues. lol The new Lyman ultrasonic toy shows up on Monday. I'm looking fwd to trying it out and seeing if really works...
Yeah; it doesn't always work out when you try something new; but honestly, I found that my experience with this Lyman ultrasonic machine pretty much mirrored that of others, as seen in a number of online videos on ultrasonic case cleaning. The case exteriors could be shinier-maybe I'll get a tumbler if I want to go there-but the insides are what I really was wanting cleaned. My resizing die was starting to get gummed up from my dirty cases. That shouldn't be an issue anymore.