M1 Garand IHC DRC Marked Windage Knob Cap Large Letters International Harvester May '54 on useM1 Garand International Harvester Windage Cap marked "IHC DRC". Large Letter on markings were observed on all of IHC production except for early pre May '54 production which used smaller lettered "IHC DRC" Windage Caps (see LAST picture of a large and small letter knob side by side for comparison and reference). These large lettered caps were also observed on Springfield rifles in the 5.35 - 5.90 mil serial number range. One pictured available. Click on image for larger view of actual part available. Last picture is for reference and shows large ans small letter knobs side by side.