Gun Reloading Animation, Mag always rotate around root bone in unreal engine

My gun is copy transform from right hand bone, the mag copy transform from left hand bone when left hand hold the mag, after export animation to unreal engine, the mag just jump around root bone, I tried a lot tutorial videos about reload a gun, even changing different gun model, always get the same issue. I use Mr.Mannequins addon for human rig. Any one knows how to fix this?

mag anim in Blender, pls dont mind the poor test anim:

mag anim in unreal engine:

Welcome :tada: ,

Why after ?? If it jumps in blender how could it be good after export ???
Maybe have a look at something like Child of contraint shot ??

I mean, picture 1 is the anim looks like in blender, the anim look terrible, but the mag leave the gun as I want, I export two anim file from blender, one for mannequin, other one for gun, gun anim in unreal engine shows as pic 2, mag never leave the gun, it just jump around root bone, looks like blender didn’t bake the gun anim completion

And “child of” way still not works, the hand moves will make a key in mannequin anim (I used auto add key), but gun anim will not make a new keyframe in gun anim automatic, even I add new key manually in gun anim, the data of the new keyframe will not “consider” or “realize” mag moved, so the anim file in unreal engine still looks like pic 2, no transition data, rotation data only.

That is because Unreal has no concept of Blenders Child of Constraint.
Solution is simple. Bake your animation before export or setup the same constraint inside Unreal.