65BR: I suspect if your brother had been zeroed to kill the deer,instead of zeroed at 100 in accordance with conremporary "wisdom",the 300 yard buck would have presented no problem.The buck would likely be dead.Animals do not wait around for you to use clicks;rutting whitetails are in constant motion.
With a flat-shooting rifle, there should be no trajectory concerns at 300 yards.
I completely agree your brother was over-engineered for the task at hand.In hunting, the "KISS" principle prevails;frequently, the method that allows you to get into action QUICKLY is the one that will prove most successful.
