Vall, I think the zip lock bags keep moist air away from the cases. I haven't had any corrosion problems on my trips.
I don't bother soaking my cases for more than 1/2 hour after decapping. It keeps the cases shiny
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I would decap and rinse in water at the end of each day but I'm a procrastinator
I used to use water and windex with vinegar for cleaning my rifles, but Kenny Wasserberger recommended Butches BP Bore Shine as he thought it helped pull out any carbon fouling in the throat. It seems pretty good. But as the one poster said, there are lots of effective ways to clean these rifles. I do like to check on them a day or two later.
The brass is the most work. I decap, drop them into soapy hot water for 20-30 minutes max. Then I clean them in an ultrasonic cleaner in two passes. One ith Hornady solution, and the other with pure water. The cases come out like new. If I want to use them in a hurry, I dry them with a heat gun on the lowest setting.
When shooting BP with a single case I don't bother with any of this. I just clean the single case by hand with a brush and soapy water. That makes for the easiest cleanup at the end of the day
Chris.