i use T7 pellets and never had a problem with my powder ...BUT i had a problem with my bullets ,i sighted in my muzzeloader in the summer [warm temperature] and at 100yards all of my shots went into a 2" circle ..went back to the range in the fall , temperature was damp and cold and i was shooting 12" low ...the DEAD CENTER BULLET sabot was not sealing enough in a cold climat ..[also noticed they were very easy to load ] had some HORNADY SST.250 gr. and was on target with them ,used same powder T7 .. so did u go back to the range and try a differant bullet ?????