as long as its kept dry from moisture and cool it will last a long while, i have reloaded shotgun shells going on 13 years old and they go boom every time
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What Would Jesus Do ????? Just Ask Him.
As said, keep it dry and cool(don't store it in the attic)and it will last a very long time. From the Fall of 1983 to summer 1985, I worked in a Hardware store where I bought 2 cases of 12 ga. ammo wholesale. Still got about 60 rounds. So far they've worked just fine.
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Do it today, tomorrow it may be illegal. NRA MEMBER