Hey Rob Gronovius,
Perhaps the intended effect was to illustrate the visual of a APT round as it wizzes towards it's intended target. No personal experience with AT Guns here, just an assumption based on what I have read. If the effects were only intended to add to the production value of the movie , it worked for me.
AP-T (armour piercing tracer): tracer unit in the base. Typical example: american M72 AP shot of 75mm used in M2, M3, M5 guns.