I've had some bounce backs resulting from impact with the offside shoulder as well. However, my amateur autopsy proved this not to be the case.
After getting her back to the house and suspended from the cherry picker, I began to skin her. I always remove the legs at the knee joint for ease of hide removal. While removing the left (offside) leg I noticed what appeared to be a gash about 4 inches up from her hoof.
As I inspected the gash I realized this was not just a gash, but a Woodsman-shaped hole. Now, while I can never be certain, here is what I believed to have happened.
Being only 13 yards away the angle of entry was quite steep. You can see in the photograph posted above there is a ruffled area of hair just behind the shoulder about 2/3rds of the way up from the bottom; this was the entry hole. What you cannot see is the arrow exited directly out of the armpit on the offside, but never making contact with any portion of the leg except for the spot I described near the hoof. Would have had a picture of the leg for better clarification if my dog had not decided to stash the leg in parts only known to him.
It appeared to me as the arrow was passing through, and the doe began to bolt, as her front leg was lifting it impacted the arrow on its way down. Where the arrow hit the leg was only tendon and bone, no meat to speak of whatsoever. So, I'm assuming this is what created the launch sequence.
What do you think?
By the way, I left the tracking video uploading overnight only to awake to an "Error in Upload" screen from Photobucket this morning. I set it to upload once again, so hopefully I can post the video when I get back home this evening.