Russian 12 inch/40 gun
Russian 12 inch/40 gun is a naval artillery or rifled breech loader.
Overview
Russian naval artillery.
In detail
It is associated with Russian Empire.
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
“Russian 12-inch 40-caliber naval gun”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q7381989: Russian 12 inch/40 gun
Consult the source