I emailed the ATF this very question 2 months ago. After 2 weeks they emailed me back stating that a gun must be in it's orginal unaltered configuration. I emailed them back and asked what if there was just a new stock or a bent bolt or drilled and tapped. After another 2 weeks they told me that a new stock or a few holes would not be a big deal, but a bent bolt would. So unfortunately, (as with all legality questions), it is pretty vague as to what will qualify. In my opinion, this is all pretty foolish considering one could buy the original configured gun and make all the altercations himself to make it a state of the art weapon. All in all, I agree that I don't think it's a huge deal to them anyway. I mean if you buy a gun from SOG that they say is C&R eligible, they're not going to lock you up and throw away the key. Those places are constantly audited by BATF and they probably know the laws better than us.
