Read this from randy wakeman.

http://www.chuckhawks.com/muzzleloading_murphy.htm

"Murphy's inline doesn't seem to shoot like it did last year. What Murphy has never understood is that flash holes erode. Once a flash hole opens up, in as little as 100 shots of Triple Se7en according to Hodgdon's own tests, internal ballistics change, and so do exterior ballistics. The amount of erosion is contingent on pressure and heat. Those three pellet loads Murphy now uses eat away at his breechplug like his old load of 90 grains by volume of Goex never did. Murphy never measured a new breechplug, and he never measured an old one, so he will never know.
Smart muzzleloaders know never to trust their hunt to suspect equipment, and realize that breech plugs are designed to be replaced. While Murphy gets ever more perplexed, the prepared muzzleloader replaces his breechplug on a regular basis.
Murphy never could be bothered to shoot through a chronograph. Velocity changes are invisible to ol' Murphy. It either goes bang or it doesn't for the Murphster; pass/fail logic is the only logic he knows. Murphy thinks that hygroscopicity is some thing like perpetual motion: he knows his bugle bleeds in dry air, humid is rain, but can't really tell much in between.
Poor Murphy. He should have learned by now that if it "cleans up with ordinary tap water," it absolutely must be water-soluble and suck moisture. Those half-empty jugs of Pyrodex and last year's T7 pellets have lost their potency, and are now prone to misfires. Murphy doesn't chrono, so he can't tell. Opened cans of Pyro and left-over partial pellet packs should be disposed of. If you want "new" performance, and "new" reliability, you need to start with fresh product not exposed to air, much less garage or basement air. Not Murphy, he "never had any problem." Few people do, until they finally do.
Murphy feels his sabots are too tight. Forget that Murphy does not know what his bore "