It's time to have HuntingNet's own version of "Myth Busters!" [8D]

Barrel "wear," or more accurately, barrel EROSION, is not caused by the contact between the bullet and the throat/rifling. The bullets simply aren't hard enough, or going fast enough, to actually wear the barrel. The cause of throat erosion is actually from the superheated, high pressure gases that are the product of rapidly decomposing nitrocellulose based smokeless powders. Just like water carved the Grand Canyon, high pressure/temperature gas carves out the rifling in the barrel a few molecules at a time, concentrated at the throat where the pressure and temperature are highest. If you notice, all cartridges that have the reputation as being "barrel burners" burn a lot of powder for their caliber (overbore) and are high pressure cartridges (60kPSI+). If you've ever shot a large volume cartridge you'll know that the barrel gets a lot hotter than a small volume case of the same caliber (i.e. .300Win Mag vs. .308 Winchester, .22-250 vs. .223 Rem, etc...). They also have in common high peak pressures. The combination of the two factors, aggravated by not allowing the barrel to cool between shots as is often the case with a varmint rifle, is what causes barrels to wear out. That's why it's critical, when shooting a magnum rifle, to allow the barrel to cool for 2-10 minutes between shots depending on ambient temperature to preserve barrel life, and why hard core prairie dog shooters rebarrel their rifles as much as once or twice a year and might take two or three rifles with them to dog town and alternate to allow them to cool.

Mike