The Sinclair Chamber Length Gauges are designed so the handloader can determine the true length of his rifle's chamber when measuring from the bolt face to the end of the chamber's neck. This measurement will tell you how much excess case length your chamber may have over published trim lengths in reloading handbooks.
The Sinclair Gauges are inserted into a fired, unprimed shortened case and then chambered into your rifle. The insert pushes back into the case when it contacts the end of your chamber. You then extract the case and measure the overall length. The gauge is made of 12L14 soft steel so it will not damage your chamber. Step-by-step instructions accompany each gauge. The gauges can be used over and over again.
The differences between published trim lengths and the actual length of your chamber can be quite significant. You could be over trimming your cases by .030 inch or more.
NOTE: The 22 caliber gauge will not work on thin-necked cases such as the 22 Hornet, 218 Bee, or cartridges based on these cases. The 30 caliber gauge will not work on teh 30-30 Winchester. None of the gauges listed will work on tight-necked chambers except for the G-243T. Should not be used in handguns, semi automatic rifles, lever actions rifles and pump action rifles.
Sinclair, Issue:4B, Page:030