Flint in your powder
I have seales one pound powder from imr and a few others , as the world is going how long will this powder last ?
Every powder has a different shelf life, but shape can tell you a bit. Ball or spiracle powders last the longest, maybe 40 or 50 years if well stored. Stick is les hardy and some flake powders are down around 10 or 15 years. This is all very vague and just a rule of thumb at best. I would ask the makers about your particular powders shelf life, they know.
In a sealed container most powders should last at least 50 years and probably a lot longer. Exposure to air or sunlight will shorten life some. I'm am using some imr4064 that I believe was made in the 40s and some bulleye made in the late 60s. Also have a few others that were made about 1970. All seem to be fine and act normal when loaded and fired.
To seal or not to seal...
This is interesting dilemma. Sealed cans have plenty of trapped air inside. But they are sealed...
If you have two cans of rifle powder from Alliant (these high cylinders with bright labels) you have an option to open them both and put all 2 lbs of powder into one can. With RL-family (-17,-19,-22 at least) it will fill almost entire inner volume and the inner air will be displaced. But the seal will be broken.
How you personally would resolve this? As for me, I always refill the cans up to the max (2.1-2.2 lbs in case of Alliant), provided these cans are from the same batch (series number at the bottom side.) Than I put that white plastic seal in place an tighten it up. If you remove it neatly in the first place, it will reseal (well, almost) the container. Helps to get rid of half of the volume for long-term storage as well.
Any opinions on that practice?
Well I think it's just as you describe, a trade off. If youíre doing this on a rainy summer day with 80% humidity in your gun room and you plan on keeping the stuff for 15 years you could have a problem. On a winter day at 20% humidity and/or itís just a yearís worth of powder I donít think you will have a problem. Some powders get weaker over time and some much stronger, both can be very bad for the health and welfare of the gun and shooter.
Originally Posted by sergeima
In 1988 my dad and I went shooting and Dad had 50 rounds 30-06 ammo he had loaded in the 1950s sometime he wanted to plink off and use the brass. He dropped 8 of these in his Singer made M1, closed the bolt, took a knee and pulled the trigger. The issuing explosion and cloud of Arizona dust and sand knocked me down from 15 feet away!! I knew Dad had to be dead, but after a very gut wrenching silence I hear ďGod *** . . . it ruined my Singer!Ē He had some splinters of stock in his left forearm and ringing ears is all, tuff old lizard.
After 2 hours of picking up the thousands of pieces of Dadís prized Singer M1 we went to his house and pulled the other bullets. The powder was a stick powder that he could not remember the type of, but in some of the rounds it was all stuck together like it had been wet. It had never been wet or out of Arizonaís dry weather since Dad loaded them in the 1950ís. We dumped a rounds powder in a pie tin and light it off to find the clumpy stuff had a burn rate like black powder (way fast!) while the rounds that looked normal had a very slow rate.
This is why I donít keep ammo, powder, or primers more than about ten years tops. This incident spooked the heck out of me and I never want it to happen to me, Iím not as tuff as the old man!!
Odds & Ends
I tend to agree with arbuck351: powder will last a LONG time, if kept in a dark, dry, cool environment. I too have some IMR4064 that is really old, maybe circa 1950 (old 1lb rectangular cardboard container with metal top and bottem). The reason I say that is about 1957 I happened to see a can of 4064 at a friends house, and by then it was ALL METAL, similar to the IMR cans we see today. Visually, the powder looks just fine, although I have not actually tried to load any ammo with it. Anyway, that old can of 4064 is setting on my shelf "for posterity"...kind of neat just looking at it. It still appears to be completely full.
I also have some WWII 30-06 ball ammo made in 1940 and 1941, and out of several dozens of rounds (maybe 50) not one misfire...all of it works just fine. It is loaded with "stick" powder, and corrosive primers.
There is a limit though. I once had an old 45/70 round that a friend gave me. The case was the old web-syle head...really old. (20's-30's???) Out of curiosity, I tried to fire it, and it was a dud. Using a bullet puller, I removed the bullet and found it to be 405gr, and then dumped out the powder. To my surprise, the powder was a strange beige color...not sure what kind of powder that could have been??? Maybe it just turned that color from age? It might have actually worked, but the primer is what malfunctioned...no "spark"...never went off.
Back in the late-50's, when I was a teen, a neighbor kid had a box of copper-cased 22 shells. That's right, copper, not brass. I watched him shoot off the whole box, and I'd guess that about 1/4 to a third were duds. Some of them that fired sounded pretty weak. Those had to be really old. (black powder?) I don't remember them making any smoke, but that was a long time ago, and my memory ain't what it used to be. Maybe some of you old timers can clue us in on when they stopped making copper-case 22 ammo?