Black powder damage

[jdm]

How do you Tell the difference in corrosion, back by the breech on a black powder barrel? I know percussion caps were notorious for this. Wouldn't powder from a flint lock also cause damage over time?  If so is there a difference in the pattern it makes? 
 JIM

[Dphariss]

How do you Tell the difference in corrosion, back by the breech on a black powder barrel? I know percussion caps were notorious for this. Wouldn't powder from a flint lock also cause damage over time?  If so is there a difference in the pattern it makes? 
 JIM

Fouling from Potassium Chlorate is far more aggressive than BP fouling.
Dan

[Majorjoel]

You will usually find deep pitting around the nipple and bolster area on a percussion gun. This will sometimes cover quite a bit of space around this region. I have seen barrels reduced along this line where the side flat is no longer there. As Dan mentioned above, it is the direct result of the fulminate contained in percussion caps of those times. Black powder damage would mainly occur when powder was burnt and fowling left uncleaned or a live charge was left (sometimes in a dirty bore) over a period of time. Once in a while we find them loaded from who knows when. This corrosion is usually in the form of rust that attacks the surface area equally without deeper pitting. It is all bad from the shooting condition of a piece, but these signs are a map for us collectors. I'm sure that I am not telling you anything here that you didn't know Jim. One of the good things about wrought iron is that it seems to oxidize slower than some of the modern steels when exposed to the elements for long periods of time. There is still hope for those unfound attic treasures!

[jdm]

Thanks guys for your response.  I was looking at a rifle the other day that was orignal flint and there was some corrosion on the barrel. It wasn't bad  just enough that you could tell.  It got me to wondering how bad it might get on a flint rifle.  I knew the fulminate in the old percussion caps was pretty rough on a gun. Guess I hadn't thought about what the black powder might due.   JIM

[mr. no gold]

Jim, something to add into the equation here is blast erosion from the cap detonation. Add to that the corrosive chemicals in the fulminate, problably of an anhydrous nature, the rust and time between cleanings, and all these factors could cause the breech go away rather quickly.
Odd though, when a flintlock was converted to the percussion system, the barrel was oftentimes shortened at the breech end. I wonder if this was out of some necessity, or just a standard procedure? As pointed out earlier, flintlocks were much kinder to the breech area than a caplock.
Dick