Dealing with a pistol threat from the side, behind the arm

Here is one of the two main option of solutions. Depending on range, natural response and the ability to close the distance with a step, this solution is chosen when a step can't be done, a body turn is natural response, this is the foundation for this technique.
Be safe,train well
p.s. for the higher level and instructors, we also got options of: immediate double control; wrap with the close arm and counter with the other (this require step not spin)