Inconsistent EBLC-Ram armor

The Ram is supposed to have lighter armor than the MBTs but I have run into a bug where sometimes the RPG, which is supposed to deal more damage than the m5, does less damage when targeting the rear that is supposed to be the weakest point of the Ram. Shooting them in the rear correctly disables the engine which should also give the most damage like it does on the other tanks but sometimes decides to give even lower damage than it would if I had shot it anywhere else. Neither of the videos show a perfect shot squarely to the back of one but still counts as a rear shot. Should be ~65 damage always when shooting the rear of the Ram and in the videos it is 35, less than the 45 that you deal when hitting anywhere else.