THis is not the name of the shotgun, but kind of barrel, made in
Belgium.
Acier means Steel, and Cockerill stands for "Cockerill-Sambre"
the name of the steel maker.
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Acier Cockerill is not the gun manufacturer, but the maker of
the steel in the barrels. It means the gun has fluid steel barrels
and not damascus steel. It probably dates from no earlier than late
1890's through 1940. Cockerill Sambre is the major Belgian steel
maker (equivalent to Krupp or Vickers)