Yeah, spliting a rabit in halves is hard to believe but I wouldn't count it out. There are lots of deeds done by athletes that were considered impossible:
Figure skaters thought a triple axle jump was impossible at the begining of their competition and now there are guys who can do four twists in a jump! Andy Rodick recently served a tennis ball that didn't bounce, it was hit so hard that it "sunk" into the clay and no one knew the rules for that because it was considered impossible! The Olympics are making new rules for Javelin throws because the athletes are throwing so far that the stadiums are not big enough to hold the event savely!
We slingers as sportmen are at a very early stage of development in our sport at this point in time. Knollslinger mentioned that his family have been using the long sling for generations using the same style exclusively and that he praticed daily for hours growing up, that is much MUCH more than most of us can say on this forum. May be, just may be, he is so far ahead of us at what we do.
I didn't see him kill the rabit and sure I have doubt about it too but I must confess that part of me hope everything he said was true. It gives me a real high standard to aim for! Who knows, may be a few decades from now slingers would laugh at our discussion and say "Rabit? Hack, we can split an elephant in two!"