Im trying to import this gun from blender swap Blend Swap | 10mm SMG (Fallout), im using version 4.8 of unreal engine. But it is freezing (or taking ages to load) at 75%. I have tried without materials and textures but still no good
without the actual file hard to say, but looking at the renders i would say it has a large poly/triangle count, and if its been exported from a slightly older version of blender without having first been scaled up then yes it will most likely take a long time to import and then crash.
to fix use the latest version of blender to export via fbx, and it would be a good idea to reduce the poly/triangle count before you export