Hi Connor,
There’s nothing as simple as just getting the chunk from a collision, but there should be two fields on FHitResult that will identify what was hit. BoneName should have some identifying information in it, as will Item. Item looks like it gets the chunk index which is populated in SetHitResultFromShapeAndFaceIndex in CollisionConversions.cpp. So if you can get the apex actor you should be able to extract your chunks from there.
Benn.