Case Trimming Machine

In the standard calibres we have to trim because, as the case gets longer with the brass flowing forwards, the case will end up too long to actually chamber in the rifle. So, we trim the case back to a set distance to give us clearance in the chamber. The length we trim back to is called the 'trim length'.a woodworking machine consisting of a lever-operated knife and adjustable guides for shearing surfaces true to any required angle.We need to trim cases because the firing and resizing cycle stretches them, and the case mouths eventually run into the front of the chamber. This essentially crimps the case mouth slightly around the bullet, restricting its release as the powder starts to burn and raising pressures.