Blackpowder arty rounds from the Civil War still go boom after 150 years of burial on southern battlefields. I have left-over lead shot duck hunting reloads from the early 80's that I'll occasionally shoot to check out a gun's POI/POA. I've kept them in old military metal ammo boxes stored in my house which is low in humidity and year round in the 70's. I would be surprised if your rounds were bad.