CAB,
Hope you don't mind but I modified your routine a bit to entmake the leader on a certain layer and use:
(list ".pline" ptstart "a" "s" ptmid pause "")
instead of
(list ".arc" ptstart ptmid pause)
Using the pline made it easy to extract the bulge and fixes the arrowhead from being skewed when using tighter angles as shown below
.
*the only real issue I've noticed is the arc gets bigger when the two endpoints are close together and the midpoint distance from them is far away....but that does not seem like a common occurrence.
Ron