Parent bone temporarily? I asked a similar question before, except this time instead of parenting objects I want to parent the gun magazine bone to the left arms wrist for a bit, then set it back to the gun bones.

My arms and my gun are all one armature, so I only have one armature in the scene.
You can use the same technique as before, but using a bone constraint.

The only difference is that you must add the constraint from Properties > Bone constraints panel instead of the Constraints panel, while in pose mode: