I threw mine out. Water is part of the process of the breakdown of bio ammo, and the last thing anyone needs is to screw up their guns trying to save a few BBs. Maybe they'd be fine, but the risk to worth ratio just isn't there.
It takes water, sunlight, oxygen, soil and temperature that creates a micro bacteria to begin the breakdown process.
Just getting wet would not make any reputable brand of bio ammo cause any issues with it being used again. 5 years ago I wouldn't suggest it when the process wasn't as refined as it is today. However for dirt, grime, slime reasons I wouldn't use any wet ammo.
After EVERY game I take all my mags and empty them in a 1 gallon zip lock bag. That way I don't have to worry what weight I was using (I use multiple weapons with different weight of Bbs). When it comes to a big game I'll hand the big bag to someone or a team mate that is running a SAW. It makes there day and the weight of the Bbs fluctuate and what better gun could you use anywhere from 0.20 to 0.32 Bbs. Give it to a SAW for cover fire.