The circle-cross is the NATO symbol. It indicates that the ammo was loaded in a NATO-approved facility and meets the NATO specifications for that round. Note that NATO specifications are not the same as US military specifications and that many NATO-approved rounds do not meet US military specs. US military specs (such as M193 and M855) have additional requirements, such as minimum velocities, that the NATO specs (like SS-109) don't have.
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.