Back in 1997 I stocked up on E through G RMS reloads. I've been using them on and off ever since, but I wondered if there is an officialexpiration date for them. They have been stored in an air-conditioned closet all these years, and they still seem to be working fine, although they have gotten increasingly hard to ignite -- about the only thing that seems to light them reliably now are Quickburst's Twiggy igniters. I did notice that the propellant grains look like they are sprinkled with talcum powder or maybe powdered sugar, but it doesn't seem to have hurt their performance once ignited. Anyone know anything about the shelf life of these progellant grains?