very very old primers....

[Dbk]

i have stumbled upon some large rifle winchester primers!!! (worth more than gold probably nowadays)

they have been stored in a dry cool place for >10-15 years probably

are they still ok to go bang??

[bladeracer]

i have stumbled upon some large rifle winchester primers!!! (worth more than gold probably nowadays)

they have been stored in a dry cool place for >10-15 years probably

are they still ok to go bang??

I found primers I bought in 1983 about six years ago and they worked just fine.

[Oldbloke]

I'd say if less less than 30years old 99% will be fine. Assuming sensible storage.

[deye243]

Haha that's not old

[Dbk]

only one way to find out.... haha.

[SCJ429]

You will be fine, I have fired 50 year old ammo and the primers worked just fine. As others have said, 15 year old primers are not old.

[straightshooter]

I still have some left over packs of primers bought in the 70's that I still occasionally use without any issues.
The lead styphanate chemistry of US made primers has been such that if they were kept in a mostly airtight container they will last indefinitely.
I don't know about newer lead free chemistries. Only time will tell.
The first line of defence in a primer is a lacquer seal which is the red or yellow that can be seen on and around the anvil.
Loaded ammunition on the other hand is different. Eventually the solvents and exudates that emanate from the powder such as the sacrificial chemicals used to prevent powder breakdown or actual powder breakdown will affect the primer. The first sign that that is happening is hangfires.