Ammo stays potent for a long, long time. For example, last year I was looking through some old gun stuff and found five paper cased 12 ga. Foster slugs--3 Remington (green), 2 Peters (blue). I know that they had to be from the early '50's when I last hunted deer with shotgun slugs. They probably would have been worth something to a collector, but I wanted to see if they were still ok. So, one day, when were going up on the hill to my range, we brought along a shotgun and the 5 slugs. Not only did they all fire, but they made a 3" group from the bench at 50 yards. The recoil was even more brutal than I remembered.