To illustrate my earlier point about inspecting a gun for general strength in relation to modern nitro proof,
especially relating to steel shotshells, I offer the following comparison.
Both these shotguns are well over 100 years old, both are 2 3/4 chambered
and both were nitro-proved in the decade prior to the start of the Kaiser's War,
the Jeffery game gun for 1 1/8 oz and the Greener E10 for 1 1/4 oz loads.

Cheese and chalk! Action bar length and overall gun weight further reflect the difference.
Both have cylinder-bored chokes and while I have every confidence shooting modern steel waterfowl cartridges in the Greener Empire,
I strongly suspect the same loads would soon destroy the Jeffery game-gun.