That is one of the silliest things I have heard in a while . So many things in the story deify logic . No one man trained 10's of 1000's of shooters . Most departments have their own training program . Toothpasting bores would have nothing to do with shooting 100 yard sniper rifles . If tooth paste could wipe out steel , nobody would have any teeth left . I work with a lot of abrasives that would remove the enamel from your teeth in short order but will not hurt steel . There are so many good products made for rifle use that work there is no reason at all to use dental products . I also feel someone was having a good laugh at your expense .