The L.E. Wilson Case Gage 300 WSM is a precision measuring tool designed for handloaders who want to avoid one of reloading's most common mistakes: oversizing brass. This single-piece case gage lets you check both overall length and datum-to-head measurement quickly and accurately using nothing more than a caliper, giving you direct control over headspace and die setup without guesswork.
Proper headspace is where case longevity begins. When you resize fired brass, you're walking a fine line—too much sizing and you're shortening case life unnecessarily; too little and you risk pressure spikes or reliability issues. The Wilson gage takes the guesswork out of that equation. Before you ever touch a die, you can measure your fired cases and know exactly what you're working with. This tool is especially valuable for setting up 7/8"-14 press-type full length resizing dies, where precision dial-in prevents the kind of generational oversizing that compounds with every reload.
Built to last, the gage features a knurled grip in the middle for secure handling and a sturdy silver-finished body. The dual-diameter design accommodates the shoulder and case body profiles of the 300 WSM, with a large end diameter of .473" and small end of .347"—sized specifically for this magnum short cartridge. Whether you're loading for a new rifle or reviving old brass, the Wilson gage is the first step in consistent, safe, and economical reloading.
Key Features
- One-piece design for quick, reliable headspace measurement
- Check overall length to assess trimming needs
- Measure datum-to-head distance for proper die setup
- Prevents overresizing and extends case life
- Works with any standard caliper for precise measurement
- Knurled middle section for comfortable, secure grip
- Durable silver finish
Specifications
| Overall Length | 2.494" |
| Large End ID | .473" |
| Small End ID | .347" |
| Outer Diameter | .991" |
| Finish | Silver with knurled center |
| Includes | Gage and instructions |
Frequently Asked Questions
How do I use a case gage for die setup?
Place the fired case into the gage and slide it in until it stops. Then use a caliper to measure the gap between the top of the case and the top of the gage at the datum line. This measurement tells you how much your die is moving the shoulder back. Record this measurement before adjustment, then adjust your die slightly and re-check until you reach your target headspace.
Can I use this gage on a progressive press?
The L.E. Wilson gage is designed to help you set up 7/8"-14 press-type full length resizing dies before you begin loading. Once your die is properly tuned, you'll use it on those loaded rounds to verify consistency. It's a setup and quality-control tool rather than an in-press measurement device.
Will this gage work for my 300 WSM ammo?
Yes. This gage is specifically sized for the 300 WSM, with dimensions matched to that cartridge's body and shoulder profile.
What do I need besides the gage itself?
You'll need a standard dial or digital caliper to measure the gap between your case and the gage. The gage itself and instructions are included.
