IDK, lizards are tough to kill quickly, 12 ton ones are probably especially tough to kill quickly. From what I've heard, you want to hit them 1/3 of the way above those little arms.
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Might be a long tracking job with no blood, but at least there should be big tracks to follow. You might need my dog.
Until that happens, the next project is a full frontal chest shot bear, but unfortunately this will have to be a black one, at least until after June 30th. I'm pretty confident of the outcome.