i use an old tupperware bowl in the sink. no magnet necessary. ok well almost no magnet necessary... i have a small neodymium magnet in a bottle cap that i put in the sink drain to catch any stray escapee's (i get maybe 2-4 every batch that try to get away)
pour the whole mess into the tupperware ( i have a big tupperware bowl, it only fills up about half way), and start rinsing with cold tapwater. once the water runs clear, i start to mix the brass up like if you were tossing a salad or mixing meatloaf. the water helps lessen the surface tension on the pins inside the cases and you end up with >80% of the pins in the bottom of the bowl.
then i go into a rotary separator for the final drop of pins to shake the last few out and knock most of the rest of the water out.
you can put your pins back into the tumbler wet - they're stainless so no harm done. have been doing that for several years now without any damage to my pins. i drain most of the water off, but dont worry about the last little bit - it'll evaporate (i leave the cover loose, cuz i'm brave/stupid like that
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i like to knock my primers out before wet tumbling with a lee universal decapper - that way my primer pockets get cleaned by the pins AND theres no corrosion for a bit of moisture being trapped in the primers after drying too.
what did you plan to use for a dryer? i have an old Ronco jerky dehydrator i use that i picked up at a yard sale. takes about 90 mins to dry 5 lbs
(pic from da web)
i also dump my "wet" brass onto an old towel and roll them around before going into the dehydrator to get the big droplets off it to speed up the drying process a bit.