Home Forums Hunting & Shooting Ask The Gunwriters I gotta dumb question.

Some powders have ingredients/additives to to reduce copper fouling in the bore. Since cartridge brass is made up primarily of copper, do these chemicals also act on the the case, as well?

Jeff

Possibly - or even probably. But remember that the case sees one firing whereas the bore sees every firing. So the bore sees a cumulative effect. The case is exposed only for as many times as it is reloaded.

(And it was a very prescient question, indeed!)

Thanks Rocky.

Also curious as to how these compounds do their thing. Do they require heat and or high pressure, or do they continue to work after firing? If so, is there something that a reloader should do to neutralize the case before reloading? Particularly of the reloaded roads may sit for an extended time, before being fired again.

Jeff

I'm no chemist, but (subject to correction) the additive is either a tin or bismuth compound. As the hot gasses pass down the bore, copper replaces the tin or bismuth in the compound. The resulting "copper somethingate" passes out the muzzle, along with the displaced atoms of bismuth or tin.

Besides bismuth or tin, the third thing that would remove copper would be an ammonium compound. But as we know how bad ammonia is for brass, they don't use that. Neither tin nor bismuth harm brass enough to warrant any special case cleaning.

Gotcha. Thanks Rocky!

Jeff

Rocky,

My understanding of how the copper erasing agent works is somewhat similar what you have written. It is only the gaseous molecular copper that is scavenged (chelated) and blown out of the bore along with the combustion gases.

Since the copper in the brass case is not gaseous (until it is exposed to heat and pressure during firing), it is essentially inert to the copper erasers compounded in the gun powder during non-firing conditions.

How much a brass case is degraded by each firing with CE powder vs. non-CE powder would be interesting to know. I suspect this has been determined and maybe someone that knows will post the answer.

Thanks. I was thinking gaseous copper, but didn't say it explicitly. Because no (or much less) copper is being deposited, any copper that's already in the bore will eventually vaporize under heat and be eliminated. So goes the theory, anyway. But cases ought to be safe, as you say.

I've used powder with decoppering agents in it a LOT over the past decade, and have never noticed any effect on the brass.

Thanks. I suspected as much but since I mostly cull cases after 5-10 firings, I could not say what happens after the 10th firing.