Originally Posted by
slamfire
I asked a Naval Insensitive Munitions expert the lifetime of primers, and he said "infinite". Well, infinity is a very long time, but in comparison to the lifetime of gunpowder, primer lifetime is not something that is tracked or worried about. The older corrosive primers would dud out in time, newer lead styphnate priming compounds, I have no idea the shelf life. I have shot 40 year old, maybe 50 year old lead styphnate primers and they worked fine.
I do believe heat is very bad for primers, and so is humidity. Primer compound is made wet and when it dries out it is dangerous. I assume therefore it will suck up water. Sealant is on the top of the primer cake so something that dissolves it would expose the primer cake to water.