GRRRRRRRRR, had to dump six pounds of IMR4320

You were lucky, or at least for now.

What you don't say is whether the rust in the container was from the powder breaking down or from another cause.

I've had cans of powder rust from the outside in an that powder is usually just fine.

When you start to get inconsistent velocities from a batch of powder with rusty dust all through it, it's not a question of is it breaking down but when is it no longer acceptable to use for such things as hunting loads or accuracy loads.

That was about 5 yrs ago. It was as I posted from the inside bottom of the containor. The powder was good and I used it all up.Very easy to tell if it is rust or the powder breaking down
 
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Not sure but after this happened to me I moved all powder that I had in tins to Hodgdon plastic ones.

It's not the fault of the tins. The powder I dumped was fine last fall but sometime between then and now, it started to deteriorate to the point it was no longer useful. I've had this happen before with powders in plastic containers as well and all were stored properly, out of any bright light and low temperature swings.

Some batches of powder just don't seem to last as long as others.

I've got an original paper container, appx half full of #4831 powder made during WWII that's just as good and consistent today as it was when I bought it over 50 years ago.
 
Not sure what was the cause in your case but in mine it certainly was the tin can because the red dust was rust., and some of my reloading friends had the same problem The plastic cans won't do this. The powder after a certain time may go bad but there will not be rust in it.
 
Not sure what was the cause in your case but in mine it certainly was the tin can because the red dust was rust., and some of my reloading friends had the same problem The plastic cans won't do this. The powder after a certain time may go bad but there will not be rust in it.

The plastic doesn't "rust'' the same color as the metal can. It will oxidize the same color as the container. Not only that, the plastic used for reloading propellants is identical to that used for liquid laundry detergent and formulated not to rust/oxidize under acidic conditions.

When powder starts to go bad, it gives off fouls smelling corrosive gasses that eat through the tin coating on the iron can and rust forms.

When this occurs in a plastic or other non ferrous container, it doesn't mean the powder isn't deteriorating, it just means there aren't any visible signs unless its gone to the next stage which will entail some ''clumping''

When using older powders it's always a good thing to give the can a ''smell test'' right after opening the lid. If you get a whiff of ammonia/formaldahyde/acid, the powder is deteriorating an can cause damage to your cartridges and bore as well as creating inconsistent ignition which results in poor accuracy.
 
You are right. With mine I done the sniff test then moved on to pass a magnet over the powder. The red dust/rust stuck to the magnet letting me know what it was. I ended up saving close to a pound of powder.
 
You are right. With mine I done the sniff test then moved on to pass a magnet over the powder. The red dust/rust stuck to the magnet letting me know what it was. I ended up saving close to a pound of powder.

There had to be acidic gasses coming off that powder to cause the can to rust.

When you start getting inconsistent accuracy, that you can't explain, toss the powder. This isn't my first trip down this road.
 
When I did some consulting work with Expro (the Valleyfield company that made propellants and explosives for the CAF and IMR) the head of R & D was a PhD chemist. He told me that powder is a poor lawn fertilizer because it would take 20 years to break down.
 
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