Main problem with BMP-1 ingame is its horrendous TacAi. At common engagement range gunner will shoot from 2A28 Grom, turn out, shoot with ATGM and start reloading cannon AND ATGM. Full reloading cycle take up to minute, and as you can guess, BMP-1 probably will not last so long on battlefield (actually its even worse, during reloading cycle driver start panic evasive maneuvers even from good defensive position). Try in QB to expend all its ATGM ammunitions and and you will feel how much more powerful it is with one PG-9 grenade every 7-10 seconds.