Barrel Life, Part II

Bullets don’t wear out barrels, the flame from burning gunpowder melts them, so heat has everything to do with whether your barrel lives or dies tragically at an early age. The other factors are the size of the powder charge and the diameter of the bore.

Prairie dog shooters burn barrels faster than almost anyone else because they shoot quickly and they shoot a lot. When you get a tube smoking hot and keep it that way, its rifling is going to erode. Big-game hunters hardly ever burn out barrels unless they use their guns for other things. I have a .300 Weatherby that I’ve been hunting with since 1965, and the bore is good for another 41 years, simply because I don’t shoot it fast, or much. And the .300 Weatherby is often cited as one of the worst barrel-scorchers.

Powder charge weight versus bore size can be explained this way: For any given bore diameter, there is a maximum amount of powder that can be efficiently burned. In .30-caliber, I’d guess it’s something like 60 grains, so if you take a .300 Weatherby magnum and stuff in 84 grains, you have what is known as overbore capacity—a comparatively small gain in muzzle velocity produced by a huge increase in the powder charge. And the monster flame this creates reduces bore life to 1,500 or less from the 5,000 you normally get from a standard .30 cartridge.

But why worry?

Melvin Forbes, president of New Ultra Light Arms, was shooting prairie dogs a few years ago and had his barrel glowing an attractive cherry red when a friend asked him if he wasn’t worried about burning it out.

“Even as we speak,” said Melvin, “people are making barrels whether we want them to or not, and it takes me five minutes back at the shop to screw one in. But I don’t get to go prairie dog shooting that often.”

And then he went back to shooting.