I ran into a couple boxes of 22lr from my wife's grandfather's house...these boxes were slightly molded, and branded with a defunct hardware store name that was barely readable. Most of the ammo had corroded to light green, yet after a quick wipe, they were tried in the Granddad's (now mine) 1890 Winchester. Every round went bang, BUT, most did not go BANG loud enough for my liking, & I was checking the bore a few times when I couldn't see the impact of the round fired. Grandpa also had a box of 38spl and this was also boxed in a moldy cardboard container, and some of the brass was a tad greenish. The 38s went bang just fine. All this ammo was found in his basement under the staircase, as was the Winchester rifle. Years of moisture took its toll on the 22 ammo and discolored the 38spl's (didn't do a lotta good for the Winchester either). I've also used ammo (22longs, 38s & 30-06) just as old, or thereabouts, found stored in a dresser drawer for several decades...no mold, no green casings, all shot well. Keep your ammo dry, and your ammo will keep, period.