To make a snake's head act realistic close up, you need more moving parts than merely head and jaw and eyes. See a good book about reptiles. You would need head, l/rEye, l/rJaw, l/rQuadrate, l/rEpipterygoid, l/rFangbone, tongue1, tongue2, l/rTongue3 . And to text edit in extra Weld commands like Bloodsong suggested once. And therefore getting rid of the bug in rendering that shows when the CR2 contains Bloodsong-type extra Weld commands, or render the model in Bryce.