Bullet/Case Sealant - Asphaltum - Gum

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Bullet/Case Sealant - Asphaltum - Gum

Postby pitted bore » Sun Sep 26, 2010 8:31 pm

The idea of using a sticky gummy compound to help increase bullet pull was raised recently in another thread on this forum recently. I'm starting a new thread to follow up on this so it doesn't get too lost or hidden in a multi-page thread.

About a year ago I was experiencing problems in getting enough bullet pull or neck tension when working with light 185-grain bullets. I thought about using some sort of goo to increase bullet pull. I was probably remembering the cal-guns discussion of loctite. I had also just pulled some 45 Win Mag bullets that were stuck in the case with Winchester's version of this goo.

So, I then started looking for the composition of the goo that is used in commercial and military ammo to seal the bullet in the case. I found some pretty obscure references in books and on the web. These may be helpful if anyone on this forum wants to experiment.
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Re: Bullet/Case Sealant - Asphaltum - Gum

Postby pitted bore » Sun Sep 26, 2010 8:32 pm

Just in case the earlier thread gets lost, the pertinent posts from it are posted here:

viewtopic.php?f=5&t=24&start=53
Siringo» Sun Sep 12, 2010 wrote:A little history first. I recent built up a rifle in the 6.8 SPC for my son. We have just starting shooting it and only had some Remington factory ammo. One round did not go off (must be loaded on the same line that their 22 ammo is made!).

Any way, I pulled the cartridge apart tonight and lo and behold, the bullet has a mastic around it to hold it into the cartridge case. It took several firm raps with the puller to get the bullet out.

We had discussed this earlier -- maybe on the calguns site -- but would this work for the 450B. Anyone want to comment?
Mike » Mon Sep 13, 2010 wrote:I recently was pulling bullets out of some lake city 09 stuff and they had this sealant and them as well. My biggest question is do I really want to shoot a bullet dipped in some kinda tar down my barrel. Same with loctite- it cant be good.
Siringo» Mon Sep 13, 2010 wrote:Gets burned off easily. Military uses it to waterproof ammo. I just thought it was odd that Remington used this on commercial ammo.

Based on reading on the NET -- this is a form of asphalt. Anyone know exactly the type of material and where to get it. We then set up HOOT to test it for us!
wildcatter » Mon Sep 13, 2010 wrote:It's called Ballistics GUM. A very similar product can be found with a product used to heal wounded trees, it too is a black gum. All Military Ammo uses it and untold trillions of rounds have not hurt any barrel. I have used it successfully, it does increase Bullet-Pull, but alas, tis difficult to apply, unless expensive production equipment is deployed. Hence, the mother of invention, created the LeGendre Side Crimp, and bullet pull became much less of an issue..t
Siringo» Mon Sep 13, 2010 wrote:I found you can use Ortho Pruning sealer. Got some in my garage and after I get 5 fired cases, I am going to glue some bullets in (cases will not be sized, primed or loaded) just to see what happens. Curiosity ya know! Even Lake City Match ammo was glued in. Just another tedious process. Maybe this can be added to using 284 brass!!!!!! That was a sarcastic joke!
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Re: Bullet/Case Sealant - Asphaltum - Gum

Postby pitted bore » Sun Sep 26, 2010 8:37 pm

Siringo» Mon Sep 13, 2010 wrote:Based on reading on the NET -- this is a form of asphalt. Anyone know exactly the type of material and where to get it? We then set up HOOT to test it for us!

Here are two answers to Siringo's question:

From the 1981 NRA book Handloading by Wm Davis, page 22:

Primer and bullet sealants minimize the risk of powder or primer contamination by moisture, gun oils, etc. Strong attachment of the bullet is necessary in military ammunition to withstand functioning in automatic weapons. Bullet extraction force is measured in ammunition acceptance tests. In factory loading some pistol and revolver cartridges, such as the .38 Spl. or 9mm Luger with lightweight bullets, increased bullet pull improves ballistic uniformity. Although sealant makes ammunition more resistant to contamination, such risk is not totally eliminated.

For many years U. S. military ammunition has employed asphaltic varnish around the bullets. The inside of the case neck is coated with the varnish just before the bullet is seated. One of the primary requirements in such compounds is that they cause no significantly increased bullet force extraction force during storage. Substitution of other materials may increase bullet pull undesirably or inhibit proper obturation of the case neck, thereby raising pressures. Asphaltic varnish is not readily available, but can be simulated by thinning asphalt with a non-polymerizing petroleum based solvent such as kerosene or naptha though such a preparation is messy and difficult to apply by hand.

Satisfactory results are obtained using lacquer around the bullet, as well as the primer. This has been done frequently in European military ammunition. Automotive touch-up lacquer, thinned to a watery consistency works well. Lacquer is applied in a narrow band around the joint between the case mouth and the bullet, after the bullets have been fully seated. An artist's brush works well for application. The lacquer coating must be thin, so that the diameter of the cartridge at the case mouth does not exceed the dimensions listed in the appropriate drawing, after the lacquer has dried. After the cartridges are placed in boxes, apply a drop of thinned lacquer over each primer with an eye dropper. Cartridges so prepared are adequately sealed for all but the most severe requirements. R.F.D.


I found an informative powerpoint presentation about the sealing process used for US military 5.56 ammo at the Lake City ammo plant.

Trichloroethane (TCA) was used as the solvent fort the neck sealant. However, it is an ozone-depleting chemical; the presentation describes the search for an acceptable alternative. The description of that search process included the ingredients of the sealant. Composition is:
  • high-grade asphalt
  • Gilsonite
  • tall oil rosin
  • benzotriazole
Gilsonite is a trade name for a mined bituminous asphalt. Tall oil rosin is a pine pitch. Benzotriazole is a copper corrosion inhibitor. These are dissolved in a suitable organic solvent for application.

The machine that applies the solvent spins the cases at 1200 rpm, which forces the sealant to spread evenly on the inside of the case mouth. Drying time is 26 seconds.

Here's the link for the powerpoint presentation: http://www.dtic.mil/ndia/2003smallarms/hawk.ppt

I don't know the proportions of the component chemicals. Maybe it's classified. But it appears to be a bit more complex than tree-pruning sealer. (Yes, I know, appearances can be deceiving.)

--Bob
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Re: Bullet/Case Sealant - Asphaltum - Gum

Postby Siringo » Mon Sep 27, 2010 7:58 am

Great info! I tried to coat the inside of a case with the pruning sealer -- let dry -- and then seat the bullet. Didn't work. This process is for very sophisticated loading equipment.

On a side note -- the discussion with TCE's was significant because of the tremendous pollution to the ground water table by these chemicals. Great solvent, but very dangerous. For several years my firm that I had participated in clean up activities at the Twin Cities Army Ammunition Plant in Arden Hills, MN. Everything from PCB's, TCE's, Depleted Uranium (Honeywell, ATK), CZ134 (radio active isotope used for prostrate cancer), and other nasty stuff.
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Re: Bullet/Case Sealant - Asphaltum - Gum

Postby wildcatter » Mon Sep 27, 2010 8:03 pm

Doc, Siringo..


I've started many of our readers down the road to efficiency, with all manor of goos, glues, and crimps, I've written about them in both in Cal-Guns and here many times. So, again I will expound about some things I have started about using sealants. Doc, gave us some really great things to ponder, I wrote some of those outlines.

I did some of that work for LC, but for us Back-Country folk, those High-Speed Application Methods are beyond most of us, but pruning sealer can be a great alternative. I found the best way for me to apply it was to use a pipe cleaner to apply the gum and then seat the bullet while still wet, so-to-speak.

This method gives a water-proof load, especially if a tooth pick is boobed into colored finger nail polish and touched, with a very small drop, to the primer, where it meets the case, capillary-action sucks the drop all around the primer pocket seal area. Bingo, sealed case, and in tests in hot water for 24hrs, ignition was totally reliable, for me anyways and everybody I turned unto this operation. It also increased bullet pull, helping with burn efficiency, but pressures do go up, so your loading practices must allow for such.

A word of Caution about petroleum based thinning agents and gums. Petroleum Agents are used to deactivate, gun powders and primers. I one time had a brick of primers, in their case, with the ends closed, in their respective individual boxes, on my bench. I cleaned a gun, using spray lubricants. After they sat for about a week, enough time to penetrate all that card-board, and the primers themselves, none of those primers worked again. The very mist in the air, was enough to deactivate those primers.

But I digress..

Hand applying any gum is allot of work, thus I tried all manor of alternatives, from Loctites to my Side-Crimp. If the goal is to be more efficient, almost anything works, and if water resistance is the goal, pruning sealer can't be beat, if you're out here in the Hinterland. But if speed and ease of application is also a goal, then my Side Crimp may be the over-all answer. But, sealants are a LC alternative and one you should consider..t
Safety First..t
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Re: Bullet/Case Sealant - Asphaltum - Gum

Postby Siringo » Mon Sep 27, 2010 8:21 pm

W -- not that I was going to seriously go down this road. I found it interesting that Remington used this on the 6.8 ammo. I have never seen this used on any other commercial ammo that I have pulled (GI excluded).
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