Ground Corn Cob Polishing Media
Choosing Cartridge Case Cleaning Media
By Duane Thomas
Once you’ve realized having clean cartridge cases for reloading is desirable, the next question to ask yourself is what sort of media you’re going to load into your Dillon vibratory case cleaner. You have two options: crushed walnut hulls or corncob. Both have their virtues.
As the case cleaner vibrates, dirty cartridge cases rub against the media with which the case cleaner’s bowl is filled, and vice versa; this causes powder fouling on cases to be rubbed off onto the media, as the media moves over and around and inside the cases. When that happens, walnut hulls and corncob will have different effects on the brass.
Crushed walnut hulls are brown in color, and they’re quite abrasive. Where walnut hull media really shines is if you’re in the habit of picking up brass on outdoor ranges, that’s been lying on the ground, being rained on, and it’s been out there for a significant amount of time. The brass, while still perfectly safe to reload, becomes mottled, and at the extreme can be solid black. Walnut media will scour off that surface discoloration and make those casings look like brass again. The resulting finish appears bead-blasted or “frosted.”
Now, when you reload those casings, the resizing die will polish about the top two-thirds of the casing, you’ll wind up with “two-tone” brass: shiny on its top portion, frosted on the bottom. If you want to be sure you’re only picking up your brass and no one else’s, this makes that very easy to do, because your casings will look like nothing else on the range.
Corncob media starts out sort of a light golden-yellow color. It’s a much “softer” media than walnut hulls; it’s not nearly as abrasive. While corncob will not visually rehabilitate darkened casings – it’s simply not rough enough to scour off surface discoloration – where it shines (pun intended) is in making casings that aren’t mottled or blackened, they just have powder fouling on them from firing, look sparkly brand-new.
So, my advice, if you’re picking up a lot of tarnished brass off outdoor ranges, and/or if you want brass that’s easily, visually distinguishable from other people’s, go for walnut hulls. On the other hand, if you want your handloads to look as much as possible like factory-new ammo, go for corncob.
Over time, the case media will darken with use, as the amount of powder fouling builds up in it. When that happens, dump the old media and replace it with new. If you don’t, the media will not totally clean the cases, the grayish smut in the media will adhere to them in a very fine, almost visually undetectable coating. You’ll know this has happened when your fingertips, after handling casings, while not the black they’d be if you didn’t clean the casings at all, do start looking a bit gray. Case media is cheap, so there’s no reason to ever let things get to that point. When case media starts noticeably darkening, it’s time for new media.
10 pound bag. Ground corn cob polishing media the best there is for that final polish.
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WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer and reproductive harm. For more information, go to https://www.P65Warnings.ca.gov