Gun reload problem, mag doesnt move

So I have done a model in blender of arms holding a pistol, all is rigged. Then I made a reloading animation in blender where a hand takes out the magazine from the hand and places a new one and then pulls the slide on the top. I exported it as .fbx and then, when I imported the model in Unity (it's rig is generic), I expected the model to have only one single animation for the reloading but it has about 20 and when I preview the animation in the Animations section arms move separately from the gun as they are not parented (they were in blender) also the magazine and the slide never moves. Does anyone knows why the reloading animation is separated into many different animations?