I had been holding this angle steadily without moving my cursor as I was tracked.
Is this an issue with my understanding of the size of APFSDS or is it an error of the game's building hitboxes
Most likely building hitbox. I know that rock hitboxes often extend further than their model.
What you see in the game is not nessissarily what the server “sees” or used to calculate trajectories and collisions.
Yeah but I had been holding the position for a solid 15 seconds I had skimmed the building before while moving so I excused that miss but this one I was holding steady
Doesn’t matter. The “map” in the server is the one that counts. Your client is just a graphical representation/interpretation of what it is told by the server. Sometimes it gets it wrong or there is desync between them and you get ghost shells and other “gaijinings” like this.