I may have to call a doctor in 4 hours because my 325 WSM erection won't go away by then (it's my favorite). Alas, I concur with the others that the grass was sucked into the wound; thought that at first glance. Was he standing in grass thick enough / surrounding his body that would potentially sucked in? It's not clear from the story but it sounds very plausible. Anyways, nice kill thanks for sharing.
