I would say that you just missed the deer. Buckshot is highly effective inside 75 yds. 3" 00 should have somewhere between 12 and 16 pellets depending on type of shell, and if you had put all of these in a 3" area on the deer you would have known if it had been hit, regardless of shot placement. So cut off your shirt tail, for you missed. But hey, it happens to us all eventually.