I just pulled a can of this out for a up comming hunt. I've used it for two hunts over the last 15 years. The last one five years ago, thats how often the muzzle loader tags are being drawn. Was going to give it a test run this week. Maybe I'll just start from scratch.
RWE and Farming
You can easily get fooled into believing that old powder does work. It may fire-off five in a row without a hitch. Then the next five may be hang/misfires. Or, it may produce good accuracy in dry weather and once moisture or high humidity rolls in, easy absorption occurs and your powder turns to mud.
Last year I fed my lawn some 12 year-old 777 powder. Spread it out real fine across my entire small backyard, a day prior to a predicted rainfall that occurred.
Nobody likes throwing hard-earned money away. But I cannot deal with suspect powders and suspect sidehammer rifles, which I sold five sidehammers last winter, all because I lost faith they would always perform/ignite at a high level, here in the very humid Great Lakes region where I live.
My ML world revolves around inlines now. My last remaining sidehammer (brassy long rifle Shenandoah), hangs on my wall. So get rid of your old powder and never look back. Keep your powder dry........ keep it current and fresh too.
Old powder may still work. But I guarantee newer/newish powder works better. You could hang-on to that Clear Shot powder for another 25 years. It may be worth $50-$100 to a ML historic museum someday......lol