I have 2 of these cases, they have the following markings:
Green anodised aluminium case:
40 MM x 53
Yellowish grey anodised aluminium case:
CRTG 40MM HEDP M440
CASE CARTRIDGE M169
What are the manufacturers and dates of these 2 rounds? This is probably a silly question but what does HEDP stand for (High Explosive what?). The modern US aluminium cased 20mm+ stuff is [proving a nightmare to identify.