Character IK hand position and bone transform problem.

Hello.

I've had created and rigged a character in Blender.

My problem is I have a gun that is animated with reloading animation,aiming,walking,sprinting,idle ( animations created in Unity ) and character ( animated in Blender -> only legs are animated -> walking,idle,sprinting,crouching) and i want to make it so the character holds the gun with his hand and not the transform of his hand ( the bone transform)

Is there a way how to do this ? I had tried adding a bone on the hand and then positioning the hand on the green cube position. (hand didn't move) I had also tried changing the mesh of the hand ( didn't worked )

This is how he holds it.

and this is how i want him to hold the gun.

I have gun with gameobjects that are supposed to tell which hand is supposed to be on that location. Blue cube - Left hand Green cube - Right hand ( Hand is positioned at its transform position )

Hands are controlled by IK.

This is my script.

  protected Animator animator;
 
     public bool ikActive = false;
     public Transform rightHandObj = null;
     public Transform lookObj = null;
 
 
     public Transform left = null;
 
   
     void Start()
     {
         animator = GetComponent<Animator>();
     }
 
 
     //a callback for calculating IK
     void OnAnimatorIK()
     {
         if (animator)
         {
 
             //if the IK is active, set the position and rotation directly to the goal. 
             if (ikActive)
             {
 
                
                 // Set the look target position, if one has been assigned
                 if (lookObj != null)
                 {
                     animator.SetLookAtWeight(1,1);
                     animator.SetLookAtPosition(lookObj.position);
                 }
 
                 // Set the right hand target position and rotation, if one has been assigned
                 if (rightHandObj != null)
                 {
                     animator.SetIKPositionWeight(AvatarIKGoal.RightHand, 1);
                     animator.SetIKRotationWeight(AvatarIKGoal.RightHand, 1);
                     animator.SetIKPosition(AvatarIKGoal.RightHand, rightHandObj.position);
                     animator.SetIKRotation(AvatarIKGoal.RightHand, rightHandObj.rotation);
                 }
 
                 if (left != null)
                 {
                     animator.SetIKPositionWeight(AvatarIKGoal.LeftHand, 1);
                     animator.SetIKRotationWeight(AvatarIKGoal.LeftHand, 1);
                     animator.SetIKPosition(AvatarIKGoal.LeftHand, left.position);
                     animator.SetIKRotation(AvatarIKGoal.LeftHand, left.rotation);
                 }
 
             }
 
             //if the IK is not active, set the position and rotation of the hand and head back to the original position
             else
             {
                 animator.SetIKPositionWeight(AvatarIKGoal.RightHand, 0);
                 animator.SetIKRotationWeight(AvatarIKGoal.RightHand, 0);
                 animator.SetLookAtWeight(0,0);
                 animator.SetIKPositionWeight(AvatarIKGoal.LeftHand, 0);
                 animator.SetIKRotationWeight(AvatarIKGoal.LeftHand, 0);
             }
         }
     }
 }

Anybody knows how to "fix" this ?