Centrefire Barrel Life And Other Topics

AND how much velocity loss there is in a 500mm barrel compared with a 650mm barrel; are stainless barrels are better than chrome-moly; and whether button-rifling is better than cold hammer-forged rifling? These questions and many more in the same vein are difficult to answer because of the number of variable factors involved.

This business of barrels wearing out is actually a misnomer because they actually erode away. Erosion (barrel wear) is caused by the chamber throat and origin of the rifling being "washed away" by hot high-pressure powder gases. Confined, these gases build up pressure - of up to 65,000 psi (pounds per square inch) in many rifles before the inertia of the bullet and the friction between it and the neck of the case is overcome. The blast of superheated gas, driving tiny fragments of unburned or still burning powder ahead of it acts like a sandblaster, simply eroding away the surface of the barrel metal just ahead of the chamber.

Barrel erosion first becomes noticeable as