Hornady Cartridge Gauge .355" 9mm Luger / 9x21

The Hornady Cartridge Gauge for .355" 9mm Luger and 9x21 is a dedicated go/no-go tool built for reloaders who need confidence that their finished ammunition will chamber reliably in SAAMI-spec firearms. Whether you're loading 9mm for competition, duty, or personal defense, this gauge lets you verify case dimensions and overall cartridge fit before you fire a single round—a critical quality-control step that takes seconds and prevents problems downrange.

Reloading 9mm means working with tight tolerances and common ammunition, where consistency matters. This Hornady gauge addresses the specific geometry of 9mm Luger and 9x21 cartridges, so you're not relying on guesswork or a handful of test fires. Check your loaded rounds against SAAMI chamber specs and catch any out-of-spec brass, improper seating, or sizing issues before they leave your bench.

Part of Hornady's Lock-N-Load family of reloading accessories, this tool integrates into a practical reloading workflow. It's straightforward to use: insert your case or finished cartridge and verify fit. For serious 9mm loaders working with mixed brass, progressive presses, or high-volume production, this gauge is a smart insurance policy.

Key Features

• Dedicated to .355" 9mm Luger and 9x21 geometry for precise fit verification
• Checks cases and finished cartridges against SAAMI chamber specifications
• Prevents out-of-spec ammunition from reaching the firing line
• Part of the Hornady Lock-N-Load reloading accessory system
• Simple, fast quality-control check during the loading process

Specifications

Frequently Asked Questions

What's the difference between checking my brass with this gauge versus just loading and test-firing?

This gauge catches problems before you invest powder, primers, and projectiles, and before you risk a potentially unsafe cartridge at the range. It's a preventive quality-control tool that saves time, materials, and your confidence in your ammunition.

Can I use this gauge for other 9mm calibers like 9mm NATO or other wildcats?

This gauge is designed for .355" 9mm Luger and 9x21 specifications. Other 9mm variants may have different chamber geometries; verify caliber compatibility before use.

Does this work for checking both unprimed cases and finished cartridges?

Yes—you can use it to verify case dimensions at different stages of the reloading process, including unprimed brass and loaded, finished rounds.

Is this part of a larger Hornady Lock-N-Load system?

The Hornady Lock-N-Load system includes compatible reloading accessories and components. This cartridge gauge is designed to integrate with that ecosystem, though it can also be used independently as a standalone measuring tool.