Hey Joe, they definitely work on jackrabbits :D
Here's a pic of my buddy's son that went rabbit hunting with me to field test them.
Hi Thomas, these were designed with stumping in mind. They are tough as nails and built with really thick trailing edges. This pyramid shape and concave tip help to limit penetration in stumps and trees and makes for easy arrow removal.
As far as keeping an arrow from snaking under grass? Not like a judo. I didn't want "arms" that would break off or snag up in brush and tall grass before my arrow got to the target. On the other hand I didn't want it to bury under grass either and not be found. What I came up with is the concave design that you see. What this typically does for me is plow through grass and dirt, allowing me to find the arrow if not flipping it. Another buddy and I shot all day in his pasture when we were testing these and didn't lose an arrow. He is hard on starlings :D
Thanks for the questions, would love to hear back from some of you that have the head and have shot it in grass.
Stan