Approved for public release, distribution is unlimited / 100 m/s). Low voltage electrical contact was not maintained for some experimental shots and non-parallel rails were the suspected cause. In this thesis, we used a non-contact capacitive sensor to determine rail spacing to within 2/kAcm10mael, so that the rails will be parallel within small tolerances. Several rails were used in these experiments: 75-25 copper-tungsten, chromium-plated 75-25 Cu-W, and chromium-plated pure copper rails. Improving the control of rail spacing and parallelity did not ensure low-voltage electrical contact for our configurations. The largest damage was observed for chromium-plated copper rails and the least damage occurred for chromium-plated 75-25 Cu-W rails. / Lieutenant, United States Navy