Hey,
In UDK days I did this using a feature called “bone break”. It did what it sounds like and disconnected two bones on your skeletal mesh allowing them to separate completely. I used sockets on the desired dismemberment locations and attached the ‘gore stump’ (as i like to call it) at the locations when the break occurs. Previously the separated limb also had physics, etc out of the door. Unfortunately it was a little odd to setup initially.
The downside to a method like this of course is that you have to plan ahead for any possible locations where the mesh can break and “pre slice” the model in these areas, so not ideal in my mind.
Here is an older link of how to do it with UDK here.
Honestly, I’m not even sure if this feature is in UE4 yet but hopefully that will give you at least a starting point and know a little better what to look/ask for.