The hot, swirling combustion gases in modern ordnance wear steel from the gun barrel, eventually rendering the barrel unserviceable. In general, wear is proportional to the flame temperature of the propellant; this erosivity is expressed as wear/shot based on repetitive firings with a given propellant.
In order to learn more of the mechanism of wear, experiments have been conducted with steel nozzles that can be removed for post-shot analysis and for which the wear can be measured easily from the mass loss.2,3 Post firing examination by Niiler4,5 revealed that a thin, tenacious oxide layer was left on the surface of the steel nozzle, the thickness of which was inversely proportional to the flame temperature of the propellant. If this oxide layer affects the wear on the subsequent shot, then it is conceivable that wear will change when propellants with different flame temperatures are fired in combination as opposed...
