ISince most malfunctions are ammo related, and most of those relate to deformed, bulging or otherwise defective brass – dropping the bullets into a gauge is an effective way to reduce the chance of a costly malfunction. These case gauges are machined from top quality aluminium, and the pockets are finished using special reamer, made to tight tolerances SAAMI specification. Since almost all chambers are slightly larger this tool is 10-20 microns larger so it works flawless. The 100 pockets allow you to drop the rounds in a lot faster than into a single or 20 gauge boxes. cutting your testing time down to less than quater of the time! Guage comes with free flip cover so you just flip your rounds to ammo boxes. No more double work. This product is a must have for any IPSC and other sport shooter. With this tool you can test 100 rnd in almost same time as you put rounds in case box. This guage box best works with MTM caseguard boxes.