Specific insert for 30 calibers for measuring the chamber length of your rifle.
 This Sinclair insert was designed to allow the shooter to determine the actual chamber length of their rifle by measuring from the bolt face to the end of the chamber.
 A measurement carried out in this way will allow you to know how much difference exists between the actual length of your cartridge chamber and the standard measurement determined by the CIP and SAAMI regulations.
 The Sinclair insert is inserted by placing it slightly inside a suitably trimmed and slightly recalibrated collar, and then just insert this sample inside the rifle and close the bolt.
 The wider end of the insert will touch the end of the chamber and will be pushed back, sinking into the case.
 once the sample case has been extracted, simply take the measurement from the bottom to the surface of the insert to know how long our chamber is.
 The SInclair insert is made of 12L14 soft steel, and will not damage the inside of the chamber.
 It can be used together with different cartridge cases for measurements on different rifles as well.
 The difference between the standard measurements often found in books and the actual length of your chamber could be significant.
 Without knowing it you may be trimming your case excessively!