Older shotgun ammo had brass casings, the plastic casings are a relatively recent development. The big question for a shotgun shell is that one end by definition isn’t sealed all that well and therefore is susceptible to moisture ingress. I don’t recall anyone finding old shotgun ammo and testing it, though.
Most older shotgun shells were made of paper with a brass base. Not many were made of all brass but there were some.
I have used old paper ammo made back in the 50s but they were kept dry for the most part. The paper shells were easy to ruin if you let them get wet. As for sealing one end that is easy if you were going to store them for a long time. Keep them cool and dry and they should be good for many, many years.
Thanks for the info. I was also wondering whether to store shotgun shells vertically (upright) or horizontally when storing long term. Plastic (even seemingly hard plastic) has elastic properties that might cause deformation over time. I'm guessing that vertical storage is preferable, but that's only a guess.
“Older shotgun ammo had brass casings, the plastic casings are a relatively recent development. The big question for a shotgun shell is that one end by definition isn’t sealed all that well and therefore is susceptible to moisture ingress. I don’t recall anyone finding old shotgun ammo and testing it, though”
Don’t forget the old paper shells. After brass and before plastic.
A few weeks ago I had some old paper 410 shotgun shells that went thru the washer and the dryer. I got a couple of grouse with them.