The muzzle voltage in a solid-armature railgun is an important diagnostic because it can provide information about the state of the rail/armature interface. Large changes in amplitude in the muzzle voltage usually indicate a transition from nonarcing to arcing contact. Medium and small amplitude changes are also observed in the muzzle voltage. Although the meaning of these is less understood, it has been suggested that these too might contain information about the condition of the rail/armature interface. This paper reports on an experiment in which features of the muzzle voltage trace were correlated to physical features of the launcher that most likely perturbed the inductance gradient of the gun. Although we could not conclusively determine which specific physical features make the majority of the contributions, our results suggest that physical features of the railgun do account for aspects of the secondary structure in our muzzle voltage traces.