Yeah, spill the beans please
well its not really easy, there might be an easier way to do it
(use 3ds max and maya)
import the weapon into 3ds max using the actorx plugin
move the weapon away from the hands
select the mesh>edit mesh>right click-Polygon
select and delete all of the mesh except the gun
right click-toplevel
delete all of the bones except for the gun AND root bone
move all of the gun bones away from eachother so that the individual meshes arent touching ie trigger,magazine,bolt
save as a .psk
new project>import the psk
export as fbx
open Maya and import the fbx
delete the bone system
select the mesh, hold right click, Face
delete all of the mesh except for the main body
export that specific piece as its own fbx
repeat for EVERY PIECE
import the body fbx into 3ds max
select the mesh and change the name to body
repeat this process for EVERY PIECE changing the name to match the part
after that import all of the pieces onto the same work space
bone where needed
select the entire project>save psk
its a pain in the ***