Head on shot

[lmcglamery]

Walking through the woods late afternoon and the biggest buck I've ever seen came walking up a trail toward me. At 75 yards, he stopped and stared, facing me. Knowing I should either shoot now or risk seeing the white flag running through the woods, I aimed at the base of his neck, right into his chest and shot. He turned and trotted away and then raised his flag and ran up a hill. Tried to find blood but couldn't and searched around the area he went into and no sign. Of course I may have pulled off a bit and missed, but wondering if anyone has experience with such a shot and finding him later dead somewhere from a wound that wouldn't produce a lot of immediate blood. Advice for finding? Naturally, if I see him soon, I'll know I didn't hit him.