Brother, I think you have re-hatched an idea that we primitive fellers already use in other arrow straightening methods, only you have it in a simpler form. When you hand straighten an arrow shaft, what you are actually doing is stretching the side that the shaft bends toward and trying to compress the side that is bending out. And then you heat it so that it takes the new form that you have streched it into. I think trying to actually strech a shaft by pulling will try to accomplish this same thing through a more simple yet difficutl method, because it is harder to pull a shaft straight than bend a shaft straight. The guy had to do this with copper though because he had no other way of doing it, since the copper would dent in if he did it like an arrow shaft.
~~Papa Matt