6 mm caliber
6 mm caliber is a cartridge or ammunition calibre.
Overview
Firearm cartridge classification.
In detail
6 mm caliber is a cartridge or ammunition calibre.
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
“6 mm caliber”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q3599663: 6 mm caliber
Consult the source