5.56 NATO cases coming out sandblasted

[Korum]

My 5.56 NATO cases are coming out of my Lyman case tumbler looking sandblasted instead of polished. I'm using a corncob media. I can live with this sandblasted look but I'd rather them come out shiny! Does anyone have any suggestions as to what I'm doing wrong? I'm not sure how long the media was in my tumbler or how many batches have been run thru it. It's been a long time since I used it.

[IMtheNRA]

You need to add some polish to the corn cob media. Any metal polish will do - just a little bit is enough.

[JeepHammer]

Korum,
Welcome to the forum.

Keep in mind that corncob & walnut media are for POLISHING.

It took me DECADES to stumble onto this myself, even though I work with metal fabrication every day...
Sometimes you can be too close to the problem.

Polishing media plugs up really quickly when you throw dirty brass in it.
Try washing the brass in soap/water first, get the greasy crud off it, THEN polish.
It polishes MUCH faster, and your media lasts longer.

Adding polish does help speed things up by cutting crud, but it will plug up media also.

[T. O'Heir]

Cases need to be clean, not shiney. So you're not doing anything 'wrong'.
However, as mentioned, if your corn cobs are dirty they won't polish no matter what you do.
You can buy a great, big, bag (18 kilos. ~ 40 pounds. That'll last for eons.) of crushed corn cobs or walnut shells in a pet supply shop for less than $20. Sold as small pet/lizard bedding.
Then, if you insist, you can put some metal or car polish in.

[hdwhit]

Sold as small pet/lizard bedding.

If you're going to use the pet shop as your source for tumbling media take a moment and make sure it 100% corn cob or 100% walnut shells and not "walnut-based" or "corn cob-based" media which will include other ingredients (often cellulose) that can, in the presence of moisture expand and leave you with a mess that you have to pick out of the cases with a dental pick.

[Unclenick]

Korum,

Welcome to the forum.

I wonder if you might be using Lyman's green corn-cob media. It does leave a slightly dull finish on brass. Their red walnut media will provide a higher polish. The green is more geared toward dirt removal.

As mentioned, you can remove dirt with water and a little dishwashing liquid. However, I recommend that if you are going to do any kind of wet washing, you buy a Lee Universal Decapping Die or similar tool to pop your primers out first. I've seen cases that looked dry turn out to have some water still in the primer pocket with the primer. Without the primer in place, they will dry within a couple of days. Just shake them in a retired towel first to get loose water out, then set them out on a flat sheet to dry. If you can't take the primers out first, you may want to resort to drying in a low oven for a couple of hours. 300°F (149°C) is warm enough and won't put you in danger of annealing the heads. You can also buy a cheap food dehydrator for the purpose, whether you've removed spent primers or not. It's just faster if you do.

[condor bravo]

The pet stores have several varieties of ground media. The kind to get is the dark Zilla brand of English ground walnut shells. Add some liquid car polish if desired. But make sure the clumps of polish are broken up before adding brass. Otherwise the clumps will embed in the cases and difficult to remove.

[Korum]

I changed the media in my tumbler. The old stuff was no good! The last batch came out just fine. Thanks for all the tips, Guys!

[F. Guffey]

I can live with this sandblasted look but I'd rather them come out shiny!

Reminds me of head space gages; there is the go and then there is the no-go, after the no-go there is the beyond (field reject length gage). 'JUST ABOUT' anything I can do with one gage I can do with the 'other two'.

Cases come in various condition starting with the worst of cases. I have purchases once fired 30/06 cases because of the patina, some were worst than that because each case came complete with a dirt dobber. For the worst of cases I use vinegar, no salt and without soap, just plain 'ol 5% vinegar. After soaking for 15 minutes I rinse in hot boiling water and rinse twice, and the tumble for an hour.

If for some reason I tumbled cases and when finished thought they looked as thought they were sandblasted I will polish the case by spinning. While spinning I would start with 3M green pads and finish with fine steel wool. When I place those cases on the bench at the range other shooters turn grain with envy. The purpose of polishing was not to show off; the purpose was to remove the sand blasted appearance of the case.


F. Guffey

Back to the worst of cases: I have purchased 30/06 cases for 1 cent each, that was 1,400 for $14.00 and then there were cases on metal links for about the same price.

[Marco Califo]

Polishing media plugs up really quickly when you throw dirty brass in it.
Try washing the brass in soap/water first, get the greasy crud off it, THEN polish.
It polishes MUCH faster, and your media lasts longer.

Adding polish does help speed things up by cutting crud, but it will plug up media also.

I avoid mucking media by cleaning de-primed brass in hot dishwasher detergent. This removes the crud and it goes down the drain, rather than mucking up your polishing media.
Then lube & size.
Then tumble the lube off and polish in one step.
Then, when your media is dirty and paint thinner no longer helps, replace the media.

[Chainsaw.]

I was gonna say to much brass in the mix will creat the sandblasted result.

[Panfisher]

I have actually used some sand blasting medieval to tumble some rough looking old cases. Came out like you described, but close your eyes and they felt smooth and clean. I simply put them into the rotation and never looked back.