A friend of mine has a fired 20mm Hispano case made by Footscray in 1955 (HS: MF 55 20mm). The case has stampings on the side, close to the head. They are at 90° to the case centre line.
Top row: ME 3 57
Bottom row: BL Iz
Am I correct in guessing the top row indicates that the case was loaded in March 1957 at the explosives and pyrotechnic factory at Maribyrnong?
I’m assuming that BL Iz refers to the propellant but is BL the manufacturer or the propellant type or lot number?
I’ve not seen this on 20mm Hispano cases before but I haven’t seen a lot of them and all of mine are either British or US made. When did this practice commence/cease?