Found a bullet shell metal detecting a gun range that was operational in the 1950s-60s, in the pic below I have placed it next to a .22 for comparison. The headstamp is MF 018 or 310, not 100% sure on the number. Any information is appreciated cheers. Hamish
I think it’s a 310 cadet casing.
Definitely a .310 Cadet case, made by No.1 Small Arms Ammunition Factory at Footscray, Australia.