That's a drawing produced by the HSCA, showing their general acceptance of the Clark Panel's siting of the skull entry wound ("inshoot"). The "outshoot" on that drawing did not come from the Clark Panel. The Clark Panel Report ("Panel Review", 1968) is here: Link (http://mcadams.posc.mu.edu/clark.txt).
The Bethesda pathologists reviewed the autopsy materials earlier, submitting a report (nicknamed "Military Review", 1967): Link (http://mcadams.posc.mu.edu/hbf.txt).
I disregard the HSCA "outshoot" site. But if you're going to use the HSCA "inshoot/outshoot" slope line to back-project a trajectory, at least consider a cone projection backwards to represent the margin of error and potential for deflection.Above: Example of back-project method. Note it doesn't show the head-wound case.
(http://jfkfiles.com/jfk/images/concl18_pic.gif) (http://jfkfiles.com/jfk/images/concl19_pic.gif)
Don't back-project using a singular line.
(https://www.maryferrell.org/wiki/images/e/e5/Photo_hsca_ex_139.jpg)
HSCA Exhibit F-139
Using a back-projection cone that they said represented a reasonable margin of error, the HSCA discover that the rear portion of the projection cone included the Oswald window. They never claimed a singular-line would trace from the outshoot backwards through the inshoot and further backwards on into the Oswald window.
If one uses the Humes/Studivan "near EOP" inshoot, there is a degree of deflection necessary to account for the entry site to redirect to the gaping exit wound site. There is also a theory that the explosive head wound in Z313 is not really an exit wound at all, but the entry wound for a frangible bullet.
(http://i68.tinypic.com/2hwlcmb.jpg) (https://s.hdnux.com/photos/16/32/56/3779511/3/920x920.jpg) Window opened more on day of assassination than how it is now at the Sixth Floor MuseumSeems enough room to position a rifle over the topmost box and acquire a target.
(http://i67.tinypic.com/5zf69h.jpg) Box Arrangement as seen inside(http://i64.tinypic.com/30jmakj.jpg) Same Box Arrangement as seen outside