Calling Bones

I am trying to call a bone of my skeletal mesh for this function, but I can’t figure out how. Anyone care to shed some insight?

I originally constrained the character’s capsule component (like in swing ninja), but it was really buggy! If my character had anything above a small amount of velocity it would glitch out and go nuts. So I am taking anew approach. I would like to constrain the character’s right arm.