The only thing I can think of is the action of blowing on the plug trying to get old powder off. Really didn't think it hurt but if any saliva got on the plug that could cause moisture. I'm also thinking it was cause of putting it in warm truck. I noticed the primer was cleaner than normal. I been getting some dirty primers when I have shot it. Maybe the the primer was more of a dud? I accidentally washed one our speed loaders last night. Couldn't believe it when I threw the powder in the fire place. It flamed up immediately. I'm at a loss and we only have 3 days left of season so way I see it we don't have time to mess with sighting in a different powder.