Quite some time ago Tom Armbrust checked pressure and speed on vintage (20s-30s?) shotgun ammo - paper cases and fiber wads. He found inconsistent speed (he felt related to primer rather than powder degradation) and some loads had an increased pressure, he felt related to hardening/stiffening of the case and wads.
If the shells have a plastic hull I would have no concerns.
I didn't really think of 1985 as "vintage", but the music WAS terrible wink Madonna had 2 of the top 5 hits that year frown

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