Black Powder Corrosion

[mrcvs]

A few questions about black powder corrosion for which I cannot find the answers:

1) Is black powder itself corrosive, in its unaltered state? That is, is it only corrosive as fired and as fouling, or is it corrosive in a non-ignited state?

2) If so, is it corrosive only to iron/steel, or to other surfaces as well? If corrosive to brass, over a long period of time, would it be possible over even centuries for black powder to eat through the wall of a brass case? If so, how long would this take?

3) In older/antique firearms pitting is sometimes evident and I have been told this is due to shooting black powder without a quick cleanup afterwards. I have also been told that early primers were corrosive. What was in the old primers that made them corrosive? Is the pitting more likely attributable to the black powder, the corrosive primer, or equally so? If using modern primers in a black powder load today, would corrosion be less rapid/less extensive than if the old primers were used?

4) When were these old primers phased out?

[dtknowles]

1. unburned black powder is not corrosive. Burned powder (fouling) is very corrosive and will damage brass and steel.

2. Unburned powder is not corrosive and will not eat thru the cartridge brass

3. Pitting in older guns could be from use with corrosive primers and smokeless powder or from the use of black powder. Delay in cleaning firearms after using black powder or corrosive primers will lead to rust and pitting. Using non-corrosive primers with black powder will not give you more time to wait on cleaning. You can search the web on primer compounds, more than one corrosive compounds and more than one non-corrosive compounds.

4. Date for the change is variable by country and cartridge.

Tim

[mrcvs]

Here is something interesting I discovered since creating this post:

http://cheaperthandirt.com/blog/?p=8

[oldracer]

I shoot muzzle loader matches with guys that are using 200 year old guns and they shoot as well as the day they were made. Their mantra is to clean out ALL the fired powder residue and most use the peroxide/Murphy's soap and alcohol mixture until patches are totally clean. A few that have hooked breeches scrub them with Dawn and very hot water and run patches until clean. Then dry the barrel interior completely and finally oil it well to prevent any rust due to moisture.

[John Boy]

1) * BP in the container with the cap tightened is not hygroscopic - absorbs water. The ignition of BP immediately absorbs water from the air - hygroscopic. Higher the Relative Humidity - more moisture absorbed
2) * Both ferrous metals when exposed to excessive moisture & brass cases if the cases are exposed to salt water. From experience, brass exposed to salt water - will leach out the copper in the brass in approximately 6 months.
3) Both: leaving the foul in the bore that became moist and turned to iron oxide - rust, plus the mercury in the primers that creates potassium chloride
4) * After around 1920 in the US, mercuric primers were no long used in commercial ammunition

[fouronesix]

For what it's worth, Hatcher notes the Canadian's Dominion I L began the phase-out of corrosive priming of 30 M2 ammo in 1945 and the US began phase out of corrosive priming of 30 M2 in 1947. IIRC the US military conversion to non-corrosive small arms primers continued into the early 50s.

[martinibelgian]

I'll add a correction - BP fouling is NOT corrsive - it is hygroscopic, and the moisture (water) is what causes corrosion.

[John Boy]

Trivia Facts: Black powder in an unopened can usually contains 0.5% of that 'dreadful compound" called H2O. Before it goes to the polishing & drying rooms - it has about an 8% moisture content

So impress your fellow shooters at the range, the next time the subject comes up

[koehlerrk]

I'll add a correction - BP fouling is NOT corrsive - it is hygroscopic, and the moisture (water) is what causes corrosion.

Right, and almost completely correct.

The biggest culprit is the potassium salts left over after combustion. Those are very hygroscopic, and just like the more common sodium chloride (table salt) a damp mixture on steel will induce rusting in short order.

Since these salts are not affected by oil-based cleaners, you have to, have to, HAVE TO USE WATER, or a water and soap mixture, to flush them out of the bore.

I have seen 200 year old rifles that have had, literally, tons, of lead fired through them, and because they were cleaned and oiled, they're in great shape today.

I have also seen a new ML ruined because it wasn't cleaned for a week after it's first range trip.

[fouronesix]

I'll add a correction - BP fouling is NOT corrsive - it is hygroscopic, and the moisture (water) is what causes corrosion.

I think I know what you are saying but... the way it's worded sounds like BP fouling is NOT corrosive and water IS corrosive. Whatever

[mrcvs]

Since salts, potassium or sodium chloride, as remaining after firing, dissolve in hot water, it seems to me as long as one runs enough hot water down the barrel to dissolve the salts, much or all of the black powder fouling could otherwise remain. Is the above a true statement? It could be that one is in a bind for time and as long as the above occurs and the barrel is dried out and oiled, proper scrubbing could occur at a later time???

[Springfield]

I'll probably burn in BPCR hell for this but whatever. I have shot a cowboy match with my pistols, rifle and shotgun and then NOT touched them at all, just put them in the safe. 2 weeks later I shot another match, put them away. 2 weeks later shot another match, and everything mostly works well, cylinders may get a bit sticky, but no big deal. I then clean all 4 guns and no rust is seen, I still have nice shiny bores. This may not work in a more damp area, I am near the coast in California. I also use bullets with LOTS of lube, may help, who knows for sure. I don't do this all the time, maybe 2 or 3 times in the last 6 years, but it proves, to me anyway, that BP will not rust out your gun in a matter of days if not cleaned immediately. I think the matter of BP cleaning is WAY overblown, kinda like the myth that you will blow yourself up if anything plastic is used in reloading BP. I do that too.

[cal50]

I think the matter of BP cleaning is WAY overblown, kinda like the myth that you will blow yourself up if anything plastic is used in reloading BP. I do that too.

It depends on local conditions and your relative humidity / moisture content.

If you are in a very low relative humidity area ( low moisture content in the air) the salt in the powder has difficulty pulling moisture out of the air to start the oxidation process. In a moisture rich environment the KNO3 ( salt ) is much more active in the presence of water / moisture.
In the desert or a state like Arizona rust is less of an issue than moist environments.


Its not overblown , its chemistry.

[martinibelgian]

fouronesix,
Spot on! Salt doesn't cause corrosion, but H2O does...

[EDG]

Only a technicality. Rust is still rust.

fouronesix,
Spot on! Salt doesn't cause corrosion, but H2O does...

[Gunlaker]

I think that most of the pitting you find in older rifles was due to corrosive primers. If you read Ned Roberts book you'll see where he talks of excellent bores ruined in short order by corrosive primers. Of course you can ruin a barrel by neglecting to clean it after using. A well cared for barrel will last much longer than it's owner. I have a couple of well cared for single shots that are 100+ years old with excellent bores. They were obviously prized posessions and well taken care of.

Chris.

[Kermit1945]

Now that this is suitably flogged, my advice: CLEAN YOUR GUNS!

Has any of this changed that?

[rmark]

IIRC, early percussion guns suffered from corrosive percussion caps.

[w30wcf]

I'll probably burn in BPCR hell for this but whatever. I have shot a cowboy match with my pistols, rifle and shotgun and then NOT touched them at all, just put them in the safe. 2 weeks later I shot another match, put them away. 2 weeks later shot another match, and everything mostly works well, cylinders may get a bit sticky, but no big deal. I then clean all 4 guns and no rust is seen, I still have nice shiny bores. This may not work in a more damp area, I am near the coast in California. I also use bullets with LOTS of lube, may help, who knows for sure. I don't do this all the time, maybe 2 or 3 times in the last 6 years, but it proves, to me anyway, that BP will not rust out your gun in a matter of days if not cleaned immediately. I think the matter of BP cleaning is WAY overblown, kinda like the myth that you will blow yourself up if anything plastic is used in reloading BP. I do that too.

+ 1. I have also left rifles for 2-3 weeks fired with black powder before cleaning them with no problem at all. In fact, they cleaned up quicker since the powder fouling was dry. This is in an atmosphere of 45% humidity.

w30wcf

[Springfield]

Kermit; cleaning your guns is always better than not cleaning your guns. The point is that just because you shot BP in your gun you don't have to rush home and clean them within hours or you will get terrible corrosion, like some people still believe. When I was Deputy Sheriff back in the early 80's we would clean our SS revolvers immediately after qualifying. We were given Stainless Steel toothbrushes to scrub the residue off. If we had ANY black on the front of the cylinder we were not allowed to go until it was gone. Now some people believe that is a terrible thing to do to a gun. Worked for us.