I thought I would post these questions because I know that there are some really smart cookies here!

My brother-in-law found an old pound of Dupont FFFFg powder in his mother's house buried in a closet, and brought it to me because he knew that I would know what to do with it. My guess is that the can is 40 years old or more. As far as I could tell, it was unopened. I opened it and checked it for any signs of degradation... and found one tiny clump at the top that broke up as soon as I touched it. I poured a small amount (about 50 grains) into a pan and did a burn test... and got a nice POOF out of it.

My questions are this: Is this still viable powder? What could this be used for? I'm planning on loading some 45/70 in the near future. Can FFFFg be used for 45/70? I also have an older replica 1858 Remington ball & cap revolver, can this powder be used for that? (I used to use FFFg, and now I use Pyrodex P). If this powder is not safe, then I'll destroy it.

Any help would be greatly appreciated.