These BG design was very long in development up to the end of 80s, planned for future tank. They indeed made longer sabot, which reduced total T-64A ammo load which was considered not acceptable by KMDB. Another problem was different charges for HE and APFSDS rounds which was also considered as a problem at that time. D-89 was planned for object 480 future tank design, also remaining experimental design. Changing projectile size and making them non compatible with previous rounds was a huge problem.