Gun Animation Issue: Not Showing Full Animation

I have created a reloading animation for a gun on Blender. I use a plugin to import and export those animations so it can work with Roblox. The animation I made in Blender looks different that the one in Roblox Studio. One big difference you can see is that the gun magazine is not moving with the arm, the bolt (at the end) is also not moving. How do I fix my animation so that, the animation I made in Blender looks exactly the same as it does in Roblox Studio? Please be kind, I am a newbie at animating. Hope to hear from y’all soon. I will include a video to show you what I mean…


Im not great with rigging but i would assume its a rig issue.