I have had Pyrodex and 777 both go bad in a year. These were stored in their original container, in a Zip Lock and then in a GI ammo sealed can.
I would not even use it for practice as the groups are enlarged and you end up thinking something is wrong with the gun. I went back to BP


If God wanted you to walk and carry things on your back, He would not have invented stirrups and pack saddles