Sounds like you need to take the time to get your "stuff" together before hunting...

Old Pyrodex can loose it's strength...Whenever changing any part of a load you have to check to see where the bullet will hit...

With a muzzleloader you are reloading each shot, everything has to same the same for a good group...

Take the time to try that gun with 777, no need to take any chances and wound a deer...