My Dear Ranger -
Please allow me to begin with the following caveats:
- No Offense intended,
- not trying to be argumentative, just offering discussion
- I am not a chemist, don't care to be, carbon rings make my head spin.
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My experience with real BP matches yours - I too have found old charges in modern repro's that were still live, and one charge in an old original barrel of which a sample of the charge "puffed" quite nicely (barrel was over 100 years old, no one knows who loaded the charge or how old it was) .
It is now my practice to treat every ML barrel as loaded until proven otherwise, and to soak any obstruction in oil liberally from both ends until any work it done.
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Whilst I will use Pyro when BP is unavailable, I have no experience with deterioration thereof....
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Your chemist friend opined:
>He stated that most nitro based smokless powders have a shelf life of about 10 years as well.
(first please reread the above caveats)
With no offense intended, my experience differs greatly.
- I recently found I have what is left of a keg of Unique from my days of attempting to shoot with a trap club. The Remnants of Said Keg is (are?) now over 30 years old. Some .38 and .45 handloads I made recently with this powder are as accurate, and have same apparent ballistics as loads made with fresh powder just purchased.
I do not have a chrony, but I don't see much point in measuring the velocity since the empiracle evidence of the 2 loads (new powder vs old ) hitting the same point of aim at 60 feet would imply little if any deterioration.
- I would expect your chemist's assertion should also apply to deterioration of powder in old cartridges. I have old cartridges I have loaded that are still hitting the same point of aim at 100 yards, and I believe many of us have and are still willing to shoot Mil Surp cartridges of 50-80 years of age....
I therefore humbly submit that deterioration of powder is more complicated than simple age, and has more to do perhaps with extreme conditions of variables such as temperature, humidity, etc.
as an example I once shot a batch of milsurp US WW1 ammo that was as good as "new", that had been documented as properly stored in a cool dry area; and in the same session shot some cheap Brazil cartridges that had experienced, shall we say, "extremely suspect storage conditions".
That Brazil ammunition gave me my first ever experiences of hangfires.
after the third hangfire I took the R/O's offer of pulling the bullets and disposing of the powder.
your milage may vary
yhs
shunka