Unknown 5.56 headstamp


Hi guys, I’ve come across two cartridges that I cannot identify.

Headstamp is “OLN” at 12o’clock and “13” at 6o’clock. Purple primer annulus and three piece primer crimp.

FWIW, one FtF I recovered has a soft point bullet seated.


Edited to include pics as my fat fingers decided to post the topic without them.



These cartridges are found in Winchester .223 55 gr PSP boxes made in Australia by Winchester Australia Limited. It seems that they used overrun cases from a military/LE contract using symbol “OLN”, which so far I have assumed it is the one assigned to Olin Australia Limited, that was the former designation of this company util 2007. In my opinion, these cases were made by ADI.