What have done towards your prep?

[Lightspeed]

My stocks go back 7 years. So far no tins spoiled. On the whole contents are meats and vegetables. Maybe we've been lucky? Storage is in simple plastic boxes with clip on lids. These are stored off-ground in unheated but frost free areas of the property. These areas are fairly temperature stable both summer and winter, so MB's expand / contract theory is probably right.

Interestingly we have not lost any preserved fruit either. Our whole stock is of the bottled variety, so maybe that's the solution for high acid content produce?

Losses we've suffered are energy bars, which dry out horribly, but remain edible ( kind of), and some of the pasta who's plastic packages have degraded and split. The pasta's still OK, but spilled within storage box.