factory loads primer leakage

[3-300s]

twice now, in 2 years with different reputable common brand 270 winchester shells, in different model 700 bolt action rifles I've had primer leakage and primers fall out of the case. both times the shells had been older (maybe up to 25 years) in original boxes kept in air conditioned houses. shells from different owners.
one gun had to be hammered open with a board. smoke coming out of the whole action. no injuries ! I always thought ammo could be stored indefinitely. but something bad is happening, any idea what is going on??

 

[KMart]

I had an instance of this same thing a few months ago when sighting in a new scope for a friend. In this case, I don't think the ammo was 25 years old. He gave me a box of what looked like reasonably new factory loads. In this case Winchester. When I opened the box, the headstamp said Winchester, but I wasn't paying close attention.
The first round sent a little smoke out of the action and caused me to look closer. When the fired case came out of the action, I checked closer. The primer leaked all the way around and the headstamp said Remington. He had placed 5 rounds of Remington at the other end of the box. On closer inspection on the remaining 4 Remington loads, it showed a slight green corrosion ring between the bullet and case neck. That corrosion most likely provided a bonding/welding affect between the bullet and case neck, causing excessively high chamber pressure.
I have no idea how old those 5 rounds were or how they were stored and cared for. He is a farmer, and may have stored them in a tractor box for the last 10 years riding around in the rain or sitting in a barn somewhere.
In my opinion, it is not a good idea to shoot older ammo, not knowing how and where it was stored. It becomes a crapshoot. Bullet and case neck bonding/welding is a real possibility with no visual warning such as the corrosion I described.
The subject of case neck and bullet bonding/welding is a subject that can cause many arguments on these shooting boards. 50% will agree with me and 50% will say I am FOS.

 

[243winxb]

shells from different owners

Reloads, not factory Ammo? Pull bullets, save bullets. Scrap the rest.

 

[3-300s]

It was factory shells, not reloads for sure.
Both owner kept the shells in their house. Bullet bonding sounds like it could be
the cause. I'll inspect the remaining ones I have. Then in the trash they go.

 

[nmkid]

I don't remember if it was on this forum but, about 5-6 years ago I gave a fellow shooter about 200 rounds of Winchester 264 Mag cases. They were loaded so, I pulled the bullets. That's were the fun started. Some of the bullets refused to release with the kinetic hammer. So, I pulled out the old Hornady cam lock. That not only got the bullets out, it also ripped off the necks on some of the cases when the bullet did not release. The bullets that did release had bunches of the "green" where it had been held buy the case. The boxes showed that they had been hand loaded in the late 60's.