Hey Russ,
I do know you have likely made, and sold, more Powder Horns than most of us will ever see in a life time.
Yeah, probably. By rough count and estimation, I would guess the total would be about 30,000, probably a bit more. Darn, I was a busy little beaver there for a while. The idea of going out into the shop and knocking out a dozen horns a day, day after day, just leaves me feeling pretty tired right now. And that's just the thought of it. The doing of it? It ain't gonna happen any more.
Assuming a Horn is well built, and is about as air, and moisture tight as can be expected from a Powder Horn....How long do you think the powder in that horn will be usable, under normal use?
Geez, I don't know, Russ. Usually when I am done shooting at the end of the day, when I get back to the house, I refill my pouch with more round ball and patches, to replace the ones I used. I refill my capper. And then I refill my horn. Then everything goes into my big "stuff box" in a cupboard in the garage. No special handling after that, and it is not a hermetically sealed cupboard, either. In my case, the next time I am going to use my rifle is about a year or two years later. I've never had a problem with powder deteriorating on me. Likewise, when I was in Idaho, I stored my powder (and powder horn) in the garage year around. Never a problem, but the time between uses was much shorter.
Another time a group of us went for a "stroll" in the mountains. It was later referred to as the Independence Creek Death March !! On the way in, a person did not notice that he had dropped his powder horn while crossing a creek that the trail went through. When we got to our rendezvous spot and started unloading, he noticed that the powder horn that I had painstakingly made for him was gone. So, we started hoofing it back, looking for the horn. Sure enough, we found it submerged in about 6 or 8" of running water. Pulled it out of the creek, pulled the stopper and pure, dry powder poured out of the spout. The horn was probably submerged about 3 hours or more.
My feeling is powder should last in a well built horn just as long as it would in the original container it came in.
Thank back in history. Lewis and Clark were out on their voyage for over a year or more. No problems that I can recall hearing about.
The fur trappers in the Rocky Mountains were out for however long. Their powder lasted from rendezvous to rendezvous.
Etc.
I believe that a good horn is a very viable way to store powder for extended periods of time.
John