Removing tar sealant from military cases


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Captaingyro
March 10, 2013, 03:26 PM
As a follow-up to this thread

http://www.thehighroad.org/showthread.php?t=700628

I thought I'd share what I've learned about cleaning the pitch sealant out of unfired military brass. I think I've come up with a pretty efficient process.

To review, I bought some of the unfired Nato 7.62 cases Wideners had for sale. The industrial bullet pullers had not been kind to the cases, and they needed to be resized. Also, I wanted to trim them all to uniform length, and both of those processes (sizing and trimming), were complicated by the tar in the case mouths. I first though of depriming and just soaking all of them in solvent, but in this market I hated the thought of trashing 1000 magnum rifle primers.

Wideners recommended using Xylene and Q-tips to swab the tar out. I found that Xylene is hard to find in small quantities, but I had some mineral spirits, so I gave it a shot. What I found out was that it took both ends of a Q-tip to clean one case, and the prospect of doing that swabbing a thousand times, using a thousand Q-tips, wasn't appealing. The mineral spirits were slow, but worked.

I came up with the idea of automating the process using a cordless drill and a bore brush, and, sure enough, it was a better, faster process. I used old, worn .30 caliber brushes, though, and found that they didn't make good contact with the neck walls. Also, the mineral spirits were still slow.

Finally, I decided to bite the bullet (Haarrrr!) and do it right. I went to Home Depot and bought the gallon can of Xylene, and the conventional wisdom is correct: Xylene is indeed the miracle product when it comes to dissolving tar. This stuff is definitely what you want:

https://dl.dropbox.com/u/517018/Tar%20project/xylene.jpg

Also, I picked up some cheap 8mm bore brushes from Brownells, and they made all the difference, providing a good snug fit in the case neck.

Here's the setup for the drill:

https://dl.dropbox.com/u/517018/Tar%20project/setup.jpg

The plastic disk is a spatter shield to keep the spray off the drill. I just used the lid from a plastic container, and drilled a quarter-inch hole in the center. The small cloth at the center is a cleaning patch. It's wrapped around the base of the bore brush to keep dirty xylene from running down into the drill chuck. To assemble, wrap the threaded end of the brush with the patch, poke it through the hole in the disk, and chuck it in the drill. The drill is then placed in the bench vice with the brush pointing up at a 45 degree angle. This allows you to hold the cases mouth-down, and keeps any Xylene from running down to the case head and soaking the primer.

Next, pour about a half inch of the Xylene into a small cup. I used a quarter-cup stainless measuring cup. This will be where a case soaks in the Xylene for a few seconds before you brush it out:

https://dl.dropbox.com/u/517018/Tar%20project/soak.jpg

Here's the process. Place a case in the Xylene for a few seconds to soak. You'll find that the tar starts to dissolve almost immediatly, leaving a dark swirl of tar in the cup. Next, take that case out, jam it down onto the brush, and put a new case in the Xylene to soak. Here one case is about to be brushed out, and a new one is soaking:

https://dl.dropbox.com/u/517018/Tar%20project/ready.jpg

Now, hit the trigger on the drill, brush out the case neck for a few seconds, then remove the case, shake out any excess Xylene, and wipe with a paper towel. Move the soaking case to the brush, put a new case in to soak, and repeat the whole process.

After about 50-75 cases, your little cup of Xylene will look like this:

https://dl.dropbox.com/u/517018/Tar%20project/dirty.jpg

Take it out back, toss it into your snotty neighbor's yard, pour a fresh batch, and you're good to go.

After I've done enough cases to fill the vibrating tumbler, I tumble them in corncob for a few hours to clean them up and remove the wet Xylene from the interior. Then they're ready for sizing and trimming.

Like any other process in reloading, once you learn the steps and develop a rhythm, you can do this pretty quickly. Without rushing I can comfortably do four cases a minute.

The results? Here's a case with the tar still in the neck:

https://dl.dropbox.com/u/517018/Tar%20project/before.jpg

And here's one after the tumbling:

https://dl.dropbox.com/u/517018/Tar%20project/after.jpg

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bainter1212
March 10, 2013, 03:55 PM
Very nice. I have used vinegar to accomplish the same task. I leave the casings to soak in tupperware full of vinegar for a couple of days, and then swab them out with Q tips. Your brush method is genius though, I must say......

ReloaderFred
March 10, 2013, 04:16 PM
I've used the brush and Simple Green method and it works well, too.

Hope this helps.

Fred

Speedgoat
March 10, 2013, 05:16 PM
Big thank you. Just put my first batch of 20 rounds I'm going to reload in my life into my tumbler. LC Match 30-06 brass. Going to pull them out and do this method before I finish tumbling them. Thanks for the tip!

USSR
March 10, 2013, 05:33 PM
I leave the casings to soak in tupperware full of vinegar for a couple of days, and then swab them out with Q tips.

Not a good idea. Ever wonder why they turn pink? That's the zinc leaching out of the brass.

Don

rondog
March 10, 2013, 05:37 PM
Why would you have to throw out the live primers after you deprimed the cases? Depriming shouldn't hurt them. I clean tarry cases, and tarry pulled bullets, by putting them in my tumbler with walnut media and a splash of mineral spirits. Let run for awhile and it cleans the tar right off. Far less labor involved.

Then I'd put the primers back in.

Captaingyro
March 10, 2013, 05:50 PM
Just put my first batch of 20 rounds I'm going to reload in my life into my tumbler. LC Match 30-06 brass.

Speedgoat: welcome to the reloading world!

Be aware that you may not have to go to this trouble with your brass. The brass that needs this treatment is new brass, i.e., never fired. The bullets and powder have been pulled out, leaving the tar that the military uses as a sealant intact in the neck. The fact that there's a live primer still in them means that they can't be soaked. (At least not with volatile solvents.)

If your brass has been once-fired, the tar was blasted out and you don't need to do this.

Why would you have to throw out the live primers after you deprimed the cases?

You didn't read the thread cited in the first sentence, did you?

These are crimped-in primers, and removing them requires quite a bit more force than de-priming non-crimped cases...enough to damage the primers, or at least render them unpredictable.

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