Rifle headspace circumstance gauges assist in proper dimension die adjustment As well as in examining circumstances for whether or not they need to be trimmed. Essential for very long case daily life, Primarily with semi-automatic firearms! Dillon Precision headspace case gauges are made of stainless steel for extended everyday living. https://spencersqkfx.theobloggers.com/44482528/reloading-components-things-to-know-before-you-buy