Does powder expire

Folks,
How long can i expect powder to be safely stored?

TIA

I bought a 20# keg of 4831 from W W 2. Paid $12 for it. I just loaded 200 rds of 6mm .was the best powder I ever used. Just wish I had some more of it

I read an article a few years back that showed a powder company testing powder that was over 100 years old. It had been kept in controlled environment but was still good with something like a 1 % difference from the original test.

Ive got a few cans working on 20 years old. Im gonna use them still some day.

As long as it is kept dry, I would believe it is nearly non-perishable.

And, if it got exposed to humidity, I would think it could be dried back out, sitting in the Texas sun, in July. Just my speculation.

It’ll most likely be good, still.

Something to keep in mind, though, is that it can dry out. It’s made with a specific amount of moisture content. Drying out doesn’t make it bad, but it can make it less dense. If you find out that it takes a lighter charge to reach similar velocities, that’s why. So, keep that in mind when working up loads to avoid a load that’s too hot. If it’s been stored properly, it shouldn’t be an issue.

I have seen some powder that has gone bad and it will change color (brown) and have an acidic smell. I got that powder in a trade with someone that got it from an estate sale along with reloading tools that dated back to the 40s. or earlier in a few of them. That powder was less than a half pound in the original container and who knows how it was stored.

Stored in a controlled enviroment I have used powder well over 40 years old that worked fine

Thanks everyone.

The shelf life on properly stored powder is that it will last longer than the shelf.

I had almost a two pound can of vihtavuori 140 that was open go bad it started to slap through the bottom of the can I threw it on the lawn makes good fertilizer

If the powder is dry and has been temperature controlled its whole life it lasts nearly indefinitely. There is no specific chemical compounds that "break down" due to the passage of time. Moist air and huge temperature swings are probably have the most detrimental effect. However if the can is sealed properly this should not be an issue. I have powder that is from 1984 that still produces the same FPS with the same load over my chronograph. (BTW- it is IMR-4350). Most smokeless powder has a coating that helps prevent moisture absorbsion. Black powder and black powder substitutes are hygroscopic and will deteriorate over time just from opening and closing the container. Still, I have some Goex FFFg that is from 1990 and it works fine but I do get somewhere around 70 FPS less with the same load as I did when the can was new. This may be from the powder or it could be from the rifle being shot several thousand rounds. Pick up a military surplus round or any commercially produced round that is ...say...50-years old. I'll bet it shoots in your firearm. Why? The powder is sealed in the cartridge. Same concept applies to the actual can of powder.

I have powder I still use that is easily 25yrs old. Just store it proper and no issues