You said he acted like he was hit..........in this case, I wouldn't give up looking for him. I shot a nice buck with my .30-06 one year and knew he was hit good, but he ran off and there was no blood, hair or anything and we lost his tracks after a ways. It took a full day and a half of "grid" searching, but we did find him. The bullet had entered high up, taking out the lungs and passing diagonally into the rear hindquarter where it stopped just under the skin. Some shots won't leave any sign, even though they are fatal. Hopefully you either missed him clean, or if you did hit him you are able to recover him.