U.S. Military headstamp "SL 4"

Hi all, I am new to the forum. I wanted to know the date of a .50BMG
cartridge I have. Headstamped SL 4. Is this 1940 or 1944? Can anyone
help?

1944, made with a 1943 headstamp die, with the 3 removed.
sam

Thank you Sam!