They may have been reloaded at one time with corrosive primers. Very difficult to tell if a case is bad. Older cases often have folded heads not solid like new brass and are much weaker.
Rifles generally have a gas escape path for this situation. Look at the hole left side of a 03 Springfield action. It's to let gas escape with out harming the shooter. Shotguns don't have a good escape path because they operate at much lower pressure . Even so Puncture a primer gas will blow back in the action around the firing pin, whole case head lets go it's likely to come out between the barrels and action standing breech.
Not a risk I would take
William
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