They want to tie it to a serial number which is more easily tracable. Remember the law that required all new handguns to submit a fired case? Doesn't seem to have done any good, so now this. I wonder how they will arrange the imprinting in such a way that it can't be polished off or otherwise altered. Barrels are easily swapped so it would have to be on the bolt face. Not much room there so the markings would have to be really tiny thus easily modified. I should look into this technology.