A lot of people have had that kind of an experience with Magnum pellets in fact some people have an inordinate amount of trouble with 777 and there are other people who just love it. Pyrodex and black [the good stuff like GEOX and Swiss] are the old reliable powders and the new Blackhorn [in the better designed guns it was intended for] is real reliable. If you do not have a modern seal breach then it says right on the can not to use it.
It works really well in my encore.