For sure they have been used on the Leopards in Afghanistan.
I don't want to go into tactics or SOPs....but they have been used.
In regards to the 76 mm HE grenades....yup, for sure they exist...I have seen them....this is not a grenade you want to launch without thinking about the consequences.....the shrapnel wreaks havoc....not only on the enemy but all the friendlies and friendly equipment within range....such as tank optics.