I have some 209 primers I bought about 5 years ago that I put in a ziploc bag and somehow they got put into my basement. My cellar is typical in that it gets moisture a high humidity at times. Do you guys think they’re still 100% reliable? They are CCI

heck, I'm shooting some shells and some primers that are more than 30 year old. No problems. I did have some paper hulled ammo that is more than 50 years old that had a few hagnfires, but that'd the extent of my "problems" with old ammo / primers.

I would venture to say try 5 at random and see how they preform. if good then you make the final decision.
MARTIN

If the ziplock bag was sealed properly with no tears in the bag I would say you're good to go. With the exception of corrosion on their medal parts they would properly work fine if they were just setting in a open bowl. It's not easy to kill modern primers.

although I've done it....zip lock prob not a good storage idea.....

Here in Louisiana, we have high humidity. I have had some in my detached workshop for almost 40ys. Still work fine.