Some diggers (and collectors) think, "Why should I spend even $15 to get a Digital Caliper -- I'm not into bullets." But actualy, super-precise measurement is very important for correctly identifying many other kinds of relics ...such as, buttons, gunparts, coins, and buckles. Besides for distinguishing between similar-looking varieties of those items... in particular, Reproductions of those items are usually not the same precise size as the Original version they are imitating. Very-exact measuring can prevent you from buying a fake. Trust me, that $15 investment will pay off, multiple times.