I've found the commercial tumbler additives like Dillon or Berry's sells work very well for cleaning brass overall, including case necks.
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I've found the commercial tumbler additives like Dillon or Berry's sells work very well for cleaning brass overall, including case necks.
All the brass I collect that isn't my own, is from an outside range. And some has been there for a little while and gets pretty tarnished. On all of it I de-prime it then I either soak it in a solution of Dawn, Lemishine and hot water, or if it's real dirty I run the brass and solution in my HF rock tumbler. ( Can't afford the SS media yet)
Either way when it comes out it is very shiny. Then after drying, I run it in my Lyman rotary tumbler with walnut shell media and Lemishine for a couple of hours. It comes out looking brand new.
Mom didn't care if behind the ears or the neck was clean but underwear - a must. I do remember a few years back an older fellow was shooting a Garand with ammo that looked like it was on the beach since WWII, he had great groups. Patina is fine, grit is a no-no.