BP_SciFi_Character; this guide calls it BP_ProjectPlayer. The example mesh is SKM_Operator; use your own mesh and a compatible IK Retargeter.
1. Add the virtual bones
2. Retarget and apply the animations
Check the result
Play asBP_ProjectPlayer and test idle, movement, aiming, weapon switching, and reloading. The hands should follow the weapon through each action. If the pose is wrong, check the virtual-bone names and targets, the retargeted layer classes, and the override assigned to Gameplay Animation.