Lee Precision Case Length Gage with shellholder 300 Winchester Magnum 90142

Lee Precision Case Length Gage and Shellholder 300 Winchester Magnum 90142

The Case Length Gage and Shellholder is a set consisting of a length gage and a dedicated shellholder, with which Lee Precision trims cases to size and squares the case mouth. This unit works with the 300 Winchester Magnum: the trim length is determined by the geometry of the gage, so it does not depend on adjustments or operator readings and remains identical across the entire batch of cases.

The case is held by the shellholder while the cutting tool rests on the gage: the cut stops automatically when the case reaches the specified length. The set acts as a go/no-go gage: if the case is not cut, it means it is already within limits. Lee states a tolerance of +.000/-.015 inches for these units. Trimming is performed after full-length resizing, when the case has elongated: returning it to the correct length prevents the case mouth from hitting the chamber and keeps the crimp consistent. The mouth is squared perpendicular to the case axis, a condition that affects bullet concentricity. The system is entirely mechanical and requires no calibration or maintenance.

Main features

• Length gage and shellholder dedicated to the 300 Winchester Magnum
• Mechanical travel stop: length is repeatable across the entire batch of cases
• Lee tolerance +.000/-.015 inches
• Works as a go/no-go gage: if the case is not cut, it is already to size
• Squares the case mouth perpendicular to the axis
• Requires no adjustments or calibration

Recommended use

The gage must be paired with a Lee cutting tool sold separately: Cutter and Lock Stud 90110, Cutter with Ball Grip and Lock Stud 90275, or the Deluxe Case Conditioning Combo 92160, which includes a cutter and lock stud, chamfer tool, primer pocket cleaner, and power grip shell holder. The Cutter and Lock Stud is universal; one is sufficient for all cartridges with a bullet diameter smaller than .475 inches, and it can be used by hand or with an electric drill. After trimming, it is advisable to chamfer and deburr the mouth with the Lee Chamfer Tool 90109.

Package contents

• Case Length Gage 300 Winchester Magnum
• Dedicated shellholder
• Not included: cutting tool (Cutter and Lock Stud 90110 or equivalent)

Manufacturer code: 90142