I was loading a box of 375 H&H with powder from an old can of IMR4064 this PM and noticed a redish tint in the powder funnel. That was after the third case. I dumped the powder on a sheet of white paper and saw very fine rust colored dust - powder from the first two cases showed the same, as did powder from the rest of the can. The 1/2 to 3/4 pound of powder probably had a thimble full of the fine dust.

A few days ago I used that same powder to load 20 rounds of full power 300gn NPs. After confirming the loads were very accurate with a scope, I used the rest to file-in iron sights on a new barrel for a 50 yard hold. Todays exercise was to have been checking the sights at 100 yds and see whether I wanted to file the flip up for 100 or 200 yards.

I have to assume the powder was in the same shape for the first loads, and certainly there was nothing about the performance feel or noise that indicated anything unusal. My first thought was rust, but is no noticeable rust I can see in the can. THe powder could be 20-25 yeards old and I had opened it loading for an Alaskan hunt about 15 years ago...

Any similar experience?

Good hunting,

If I found red dust in my powder, I would not use it. It's one of the first signs of degradation.

Two important changes warn you of deteriorating powder - change in color to red or orange .An acrid smell .Don't confuse this with solvent smell. Either of these changes means discard the powder !!! You can spread it out in the open or better spread it on the lawn , makes good fertilizer !

Thanks for the analysis and advice.

It's fertilizer now, and I'll look closer for similar problems in the future. Actually the light had to be quite good to discern the discoloration...

What kind of climate has the powder been in the last 25 years? Did it see large temperature swings? I would normally expect powder to last longer than that.

The reddish tint was most likely rust from the inside of the can. No big deal at all. Pretty common in states with a humid climate.
When powder brakes down the grains will crumble or have a "funny look" to the grains almost like a swelling. The grains may turn an orange shade,but the grains will be deformed as if they are melting.
The odor as stated above will,be very acrid and unpleasant to the nostrils,not smell like solvent. The powder may even fume. (I have seen this.)
In the 50 years I have been reloading I have only seen two lots of powder that were bad due to deterioration. One was war time Italian Ballistite in 6.5 Carcano ammo made by slave labor and the other was 1960's .50 BMG powder that was poorly made and never was washed of the nitrate acid properly and sold as surplus.
I still load and fire my many pounds of Cordite from WWI that has been properly stored all these years. It still loads and fires as it it should.

Mystery solved. Lot's of rust inside the can that I couldn't see until cutting the can apart.

I don't know how old the powder was, but certainly not as old as the pound of H4831 in a mainly cardboard container with a $1.97 price tag still on the side. That powder still looks fine. Those powders lived in lots of places over the years including high desert, central plains, eastern seaboard and gulf coast. They probably saw very few temperature extremes but certainly some happened...

The rust may serve as bore polish.