Gut shots don't leave a lot of blood(like I said before specks and green bile coloured sign). Even if the bullet performed perfectly a gut shot is going to leave a poor result, trail and tougher follow up. I have seen deer hit vitally with good shots that left poor blood trails and are work to find, but that is part of the sport-tracking. If you have snow coming down a large grid search or look for scavangers is your best bet at finding this animal. All you can do is try and hopefully learn from the experience for the future.

good luck