While trying to find effective ways of cleaning my rifle, I paid little attention to my cases. I would shoot them, place them back in my plastic ammo box, and bring them home to reload.
Then I would spend hours trying to clean them with soapy water and little bottle brushes, and washing out my ammo box.

A friend told me he placed his cases in a plastic bottle of battery acid for a few minutes. I tried it, and it did clean the residue from my cases, but it discoloured the cases, and I thought it was rather dangerous.

I then tried dunking them in a solution of vinegar and water. This worked well, but still discoloured the cases. I then gave them several cycles in an ultrasonic cleaner, which made a very good job, but they still needed a final clean with metal polish.

Eventually I tried a solution of bicarbonate of soda. This worked well, but my cases still needed a final clean by hand.
I then found a powder called 'Bruclens', for cleaning and sterilising wine brewing equipment. I started experimenting.

I now take a pint plastic milk bottle onto the firing point, with a solution of water, a teaspoon of bicarb, and a generous pinch of 'Bruclens'. I place my cases into this solution immediately after they have been shot. When I have finished shooting, I give the bottle of cases a good shake, and bring them home. By now the water has turned black, and the cases are quite clean. I decap them, and give them another soak in the same mixture, for perhaps another hour.
I then rinse them in clean cold water. If there are any that are still a bit dirty inside, I give them a quick blast in the ultrasonic cleaner. I then give the whole batch a swill off in clean water, and leave them to dry.
When dry, they get a final polish in a tumbler, and they are ready to go again.