Summarizing the recent thread re: Mag-10: Chris Shugart says it should last about 2-3 years, longer if you refrigerate it. Technically, he’s talking about the upcoming new-and-improved version, but I’m sure this advice pertains to the old.
If there’s any danger of it getting too warm where you would normally store it, I’d say put it in the fridge.
im pretty sure old Bill R said that you could store it in the fridge if you were looking for a longterm storage option. go ahead chuck in the fridge, just dont forget about them, or get pissed and start doing MAG10 shots hehehe