BK 5
BK 5 is an autocannon or artillery model.
Also recorded as Bordkanone 5.
Overview
50 mm autocannon aircraft armament.
In detail
It is associated with Germany.
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
“Rheinmetall BK-5”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q4835806: BK 5
Consult the source