There is an impulse applied to the head when the bone break happens. One can increase this impulse so that the head is flying off further.
To change this have a look at the "IsBeingExecuted_Broadcast" event. This event spawns a Blueprint actor: "BP_Ragdoll". The Blueprint offers a few different options. Here you can decide whether a bone break is applied for head (head gets cut off) and how strong the impulse is which is applied to the head.
