I don't know if the practice is still followed or not but, during WW II
, a lot of ammo was color-coded by the user for identification on the target
sleeve as to who was getting hits and who wasn't..
It was a common practice on 30 cal ammo, can't remember for sure on 50 cal..
It was always 'ball ammo' that was tip-dipped.
This may help explain the yellow color.
Regards,
Glen