.50 cartridges with light alloy case


Here two .50 cartridges with light alloy case

The first is headstamped FA 55.
The second does not have headstamp.
Can anyone give me informations on this cartridges, specially the right one.



The right is by Winchester or more properly Olin, also found with a WRA / date headstamp & also ca. early 1950’s. (also found loaded with a red tipped tracer bullet in the unheadstamped variation)
Easy to ID their product with the 4 circular dot primer annulus application which spilled onto the head around the primer. I’ve also seen these with beveled edges to the rim. Not completely around the rim but just parts of it. I’ve asked the why of that & no one has come forth with an answer.