16"/50 caliber Mark 2 gun
16"/50 caliber Mark 2 gun is a naval artillery or BL 16 inch gun.
Overview
American naval artillery.
In detail
It is associated with United States.
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
“16-inch/50-caliber Mark 2 gun”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q4551077: 16"/50 caliber Mark 2 gun
Consult the source