40S&W Case & Ammunition Gauge - For Checking Your Reloads & Ammo The Shooters Box case and ammunition gauges are manufactured right here in Malden Massachusetts, by American workers on American machines! Unique headspace measuring 'groove' built in to the face of the gauge 40S&W Case & Ammunition Gauge - For Checking Your Reloads & Ammo Measures acceptable diameter, case length, overall length and headspace NEVER ATTEMPT TO RESIZE LOADED CARTRIDGES. THIS IS EXTREMELY DANGEROUS AND COULD LEAD TO AN ACCIDENTAL DISCHARGE CAUSING INJURY OR DEATH.