That’s a question on the same order as the old debate about how many angels can dance on the head of a pin. How big is the pin? If it’s as big as some of Flo Ziegfield’s sound stage sized pins quite a few angels can dance on it.
But there have been a few comments floating around to the effect that ammo starts going bad after three years. It’s been a while since I exercised the Blackhawk, so I threw 100 rounds of ammo I loaded in 1975, the Oehler, and a Blackhawk and headed for a friends gravel pit.
According to the slip in the box, these 210 grain jacketed pills were seated over 11 grains of Unique in front of Remington large pistol primers. The first 50 rounds chronographed 1140 fps, with a standard deviation of 24 fps.
34 years later, the next 100 went downrange at 1138 fps, with a standard deviation of 22 fps. That is well within tolerance for fresh ammo, so I would say 34 years has done nothing at all to reduce either their effectiveness or accuracy.
However, these loads have been kept below 72 degrees at less than 30 percent humidity. Those same loads locked in an automobile trunk would probably start to show performance differences in just a few weeks or months.
And stored with exposure to solvent vapors,it’s quite possible that they could be useless in a very short time.
So how long ammo will last depends on storage conditions. 100 year old ammo that’s been kept under optimum storage conditions may still perform “as new.” And last years ammo that’s been locked in the trunk over the summer should be used for feeding and firing pin checks.