To adjust hands and a weapon with the IK system, open the adjustment scene by pressing [Tools -> USK -> Adjust], place a weapon or a few weapons to the Adjustment script and press the [Play] button.
To set the position and rotation of a weapon in the hands, just move and rotate it as you need.
These slots are needed to use weapons with various views and different characters. For each view and each character, you can create a slot and use them separately.
Adjust positions and rotations of the character's hands with IK handles.
It's the usual weapon state when a character is being idle, walking or running.
Move and rotate the red cubes to adjust the hands. If you toggle the [Disable IK in normal state] , the IK system won't be active in this state.
It's the state when character is aiming.
Use the blue cubes to adjust the hands.
It's the state when character is near a wall or any tall object.
Use the yellow cubes to adjust the hands and also you should edit the "Collider to check".
This state will be useful for the third-person view if in the crouch sate your character's hands are in the body - see the image bellow.
Use the pink cubes to adjust hands. If you toggle the [Disable IK in crouch state] , the IK system won't be active in this state.
Move the green spheres to adjust direction of elbows.
There you can adjust the fingers rotation offset as you need.