As in description.
Ballistic is unrealistic for 6,5mm coaxials, you can fire 6,5 coaxial at ranges more than even 1500 meters. In reality even 7,62 coaxials have big problems above 1000-1100 meters. Only 12,7 coaxials can in reality shoot above 1200-1300 meters, but only tanks with 12,7 coaxials i know about are Leclerc and M1A1 with CSAMM modyfication.
In reality firing weak 6,5mm bullets up to 1800 is impossible.
Here is video from most realistic armor simulation: https://www.youtube.com/watch?v=jaRrzIVM9bI
Notice that 7,62mm coax has highly reduced damage and extremally high bullet drop.