I have a 40/65 and use both Starline and Winchester brass made from 45/70 cases. In the past I have used a Thumlers Tumbler and SS pins to clean my brass, just water with a small dash of Lyman Turbo Sonic case cleaner added to the mix. my local gun shop no longer has any of the Lyman product in stock. I have read here that you can add a little Citric acid to the water and it will achieve the same result .  My question is, just what type of stores sell that acid ?.
Cheers 
mike.

Mike,
If you want your cases to look brand new, inside and out, use Dawn dish soap and a squirt of Lemmi Shine.
JKR

Wet tumble with Stainless steel pins, Dawn and a little lemmi-shine. If you want them to look like new, tumble for at least 3 hours.  However, if you forget about the 1000 9mm cases you tumbled for about 10 hours you have some really shiny brass!  Set your timer.

I have just used walnut shells in my vibrator case cleaner, Let it run all night and they come out bright and shiny.

I been shooting BPCRs (40-65 & 45-70) since 1997 & attend 1 to 2 silhouette matches a month since 2012.  The brass has been in a Tumlers Tumbler with either stainless steel pins or ceramic media & I've tried several solutions.  Here's an article on the subject I wrote a couple of years ago.
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Wayne

Citric acid is available on AMAZON.

I like using Cascade dishwasher detergent gel or a cascade pod. The pod is a little too much in the large capacity Frankford Arsenal tumbler but it works.
When the cases are clean I pour them in a 50 mesh classifier that fits a 5 gallon bucket and let it drain off. The 50 or 70 mesh screen will hold the 3mm ceramic balls or SST pins from falling through.

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If I have pins mixed with the ceramic I use one of these prospecting magnets. 
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The drained water from the tumbler I save. I just keep adding more till the bucket is full and use it over and over. The dirty water clears up in a day or two and looks unused. About twice a year I pour off the water easy till I get close to the bottom and clean the mud out and pour the mix back in and add new to the clean old till the bucket gets full again and keep using it over and over.
It's not for saving money it just plain works.

Kurt

No 7, they are still around in the old British Empire and the ones in S. Africa have excellent cafeterias.