[HELP] Bones get misaligned after exporting - How can I set this up properly (easy setup)?

Hi, I have am playing around with the third person template and been trying to set up a rifle for the mannequin to use/carry. I have a rifle that I have skinned with 3 bones

-Root -Magazine -Trigger

Two of the bones are linked to the root bone, which is zero’d on its location and rotation.

all of my bones get moved around whenever I export my rifle UE4. I feel that I am either missing a step, or that I am setting this up in a wrong way all together and cant figure out what is going wrong.