Maybe too late now, but a dog may have helped in the recovery. I would suggest a mental game tape review to see if there are a few things that you might change/learn from the experience... That's all I'll say.
wow.. just read through all these posts. what a following! on far shots like that i feel like your better off letting them go reguardless of your skill. but if your sure your sure, no right to judge someone on their decisions. hope you really worked your butt off to find him though. if you shoot the animal you have to give it the respect of a proper and full hearted try at recovery not just "welp hes not laying where i shot him ill get em next time". if it were me id keep looking.. like others said get the dogs
