WW2 1942 British Dated 20mm Oerlikon Ammunition Shell Casing in
Cartridge case identification - General Ammunition Collector Discussion - International Ammunition Association Web Forum
WW2 1942 British Dated 20mm Oerlikon Ammunition Shell Casing
Heavy Ordnance Catalog
WW2 1943 British Dated 20mm Ammunition Shell Casing
20 mm hi-res stock photography and images - Alamy
Cartridge case terminology and identification – Stephen Taylor, WW2 Relic Hunter
Need info on 20mm shell - General Ammunition Collector Discussion - International Ammunition Association Web Forum
WW2 1942 US Dated 20mm Ammunition Shell Casing in Ammunition
Cartridge case terminology and identification – Stephen Taylor, WW2 Relic Hunter