Armstrong Whitworth 12 inch/40 gun
Armstrong Whitworth 12 inch/40 gun is a rifled breech loader or naval artillery.
Overview
British naval artillery.
In detail
It is associated with United Kingdom of Great Britain and Ireland.
Sources
Each source is named with the standing the house places on it, so the evidence can be weighed rather than taken on trust.
reference work · Reputable secondary · Wikipedia
“Armstrong Whitworth 12-inch 40-calibre naval gun”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q4028489: Armstrong Whitworth 12 inch/40 gun
Consult the source