IMR 4166 - odd residue

[big5ifty]

Some time ago I had noticed a peculiar smell when I opened the powder safe. I also found an unusual buildup of what looks like rust on the inside of the door.

Putting together some loads the last of the IMR 4166, I noticed the fine residue. It's finer than talc.

No idea what it is, but something like that can definitely accelerate the formation of rust if it absorbs moisture.

I checked the other IMR powders I have left, they don't have that problem.

The color of the dust is clearer on white. The second picture is the inside of the powder measure when empty.

I'm guessing the smell is the result of a slow reaction causing the dust to form. The 4166 has been sitting quarter full for at least 5 years.

[Tripodmvr]

Have you shot the cartridges that you loaded with the propellant in this state?

[big5ifty]

I have, velocity is not degraded, no misfires, no velocity spikes.

I had loaded some rounds from this a couple months ago, and I only poured as much as I needed into the measure, there was no 'powder' from the container then.

This time I up-ended the container into the measure, and the fine residue came out with the last of the powder, so it was always there, at the bottom.

[Tripodmvr]

That propellant suffers from dandruff. If the performance has not been affected the go for it.

[big5ifty]

So the batch prior to this was uneventful.

This batch gave 6 misfires from 22 rounds.

There was a lot of green, and these were reloaded 2 days ago.

Whatever gas is coming off there is reacting with brass, you can see where it came out around the primer and formed the green.

The one misfire built up just enough pressure to dislodge the primer when un-chambering.

The second pic is an unfired round, pulled.

The third is a pulled misfire, something happened, the powder turned to dust, and came out of there in chunks.

The last pic shows the green on the bullet as well.

I pulled all the rounds, including the unfired ones, cleaned all the pulled bullets with isopropanol, and put all the brass that was in contact with the powder, fired and unfired, into a sonic cleaner.

If you have any IMR 4166 lying around, it may be a good idea to use it as plant food.

[oafpatroll]

That's crazy. I'd be too nervous to ever use the stuff again.

[big5ifty]

Does that green stuff not look very much like the 'bullet weld' we find in very old ammo ?

[oafpatroll]

Does that green stuff not look very much like the 'bullet weld' we find in very old ammo ?

Yes it does to me. Looks an awful lot like copper carbonate verdigris or 'copper rust'.

[janfred]

To make nitrocellulose, you have to treat cellulose, usually  cotton, with nitric acid. They can never remove quite all of the unreacted nitric acid, hence the expiry date of extruded powder. Storing powder at elevated temperature exacerbates it.

Seems like the batch that you have contains slightly more acid than usual. It may have been stored at very high temperature before you bought it and started sweating.

[big5ifty]

The Enduron line of powders, of which the 4166 is one, was discontinued by Hodgdon around 2022, and no specific reason was given.

They were marketed as the temperature stable version of IMR powders, so there was most likely a chemical difference.

This is not exclusively a one brand problem, I've come across a few instances in the forums over the years where people have asked about a funny smell coming off the powder.

[Treeman]

I have when dealing with old propellants given to me from estates quiet often found a white substance ON the powder and identified it as a fungus. I may be wrong !
I have also seen the following, remember in school when you grew crystals ? Well, just like that, kinda growing crystal marvels like stalagmites in a cave, fine fine white pillars growing on top of propellant.
It was likely only because I opened the can without moving it that I saw it as it was, if I had move the can I would only have seen a white powder.

I quickly googled this,
  https://www.google.com/search?q=cellulose+fungus&sca_esv=5ae40a1c31d56792&hl=en-ZA&sxsrf=AE3TifNfw0-L_ylEj-4U8FBc81z5T4hseQ%3A1755506496270&source=hp&ei=QOeiaKH1DuK_hbIPyNaakQI&iflsig=AOw8s4IAAAAAaKL1UIk1CCKETORmrz9tH3YU0FrZ9F9v&oq=cellulose+fungus&gs_lp=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&sclient=gws-wiz