The KM Shooting Custom Size gauge pins are precision ground rods of exact size to allow the Handloader to insert into the necks of their cases after resizing and/or expanding to determine if the inside size is actually what they want or expect. Gauge Pins are used for qualifying the internal consistency in the sizing of your brass. Lots of internal size variations occur inside case necks after resizing. Not necessarily because of the resizing either. The Handloader doesn’t often have an opportunity to test or get a feel of real size of the inside. These variations are all because of the nature of the particular Brass being used. Large variations is quality, thickness uniformity, ‘spring back’ in different areas exists in brands and types of brass cartridges cases.
For example; Many brass cases develop a thickening on the inside towards the bottom end of the necks. Sometimes called ‘a donut’ but actually there are other thickenings that occur in different areas of the case necks. All of which impacts on bullet seating and consistency of bullet grip. The use of special internal neck expanders does not always leave the internal size remaining as you may expect. Brass spring back variations are separate from expanding. Many Handloaders can feel or do detect a variation when seating their bullets, but how much, where and why has been hard to detect, separate or sort until now.
The Gauge pins are available in sizes of 1/2 thousandths of an inch increments. See the drop down list to chose your sizes which is in decimal of an Inch. Sizes ARE NOT METRIC.
For example; the size shown as “2615” means the measurement is 0.2615″ which is 2.5 thousandths of an inch under the bullet size for 6.5 caliber (264). Or a size of “2620” which is only 2 thousandths of an inch undersize the 264 caliber size.