Generally, modern propellents and primers when properly stored in a cool, dry environment, will remain stable for many years. Some military ammo can be suspect, especially stuff made during WWII and Korea as the propellent and primer materials used at that time could break-down and the storage of it after the war wasn't the best. At the time they weren't too worried about shelf life. I have shot-gun shells of the cardboard variety made in the 1950's that still fires reliably. They've been stored in plastic bags that have been placed in ammo cans in a cool dry place. I think your JHP ammo is safe to shoot, but I would probably suggest using up the older stuff in practice and carry with more recently made batches. Really, the most important concept with old ammo is storage. If it has been repeatedly subjected to warm, moist air or direct sunlight for any length of time any ammo could be suspect. But, beyond that it should fire reliably.
