The Hornady Lock-N-Load® Overall Length (O.A.L.) Gauge – Curved Model (C1550) is a specialised, non-powered mechanical reloading tool designed to measure the exact overall cartridge length where a specific bullet makes contact with a rifle barrel's rifling lands (the zero-jump point). Featuring a contoured body, this curved tool inserts directly into the firearm's chamber through the ejection port, providing critical access for actions where straight inline chamber access is blocked. It operates using caliber-specific Hornady Lock-N-Load Modified Cases and standard vernier or digital calipers, capturing precise, bullet-specific ogive contact points rather than generic factory profiles.

Key Features

• Ejection Port Access: The curved profile enables direct chamber entry on semi-automatic, lever-action, and pump-action firearms where straight-line rear access is obstructed.
• Precise Zero-Jump Measurement: Uses the handloader's actual projectile to establish the exact rifle chamber seating depth and bullet jump clearance.
• Throat Wear Tracking: Enables target shooters to track and record firearm barrel throat erosion over time through repeatable physical chamber measurements.
• Passive Mechanical Design: Operates entirely without batteries or mains power, functioning as a purely mechanical benchtop hand tool.

Product Specifications

• Product Model: Hornady Lock-N-Load® O.A.L. Gauge – Curved Model (C1550)
• Measurement Precision: Repeatable and accurate to within 0.001 inches (0.0254 mm)
• Packaged Weight: Approximately 1 lb (0.45 kg)
• Action Compatibility: Semi-automatic/autoloader, lever-action, pump-action, bolt-action, and single-shot rifles
• Required Tooling: Hornady Lock-N-Load Modified Cases (caliber-specific) and standard calipers (optionally with a Hornady Bullet Comparator)
• Power Requirements: Manual mechanical hand tool (0W / No batteries required)

Who is the Hornady Lock-N-Load Curved OAL Gauge for?

• Precision rifle handloaders loading for semi-automatic or lever-action firearms — Need to establish bullet seating clearance through ejection ports where straight inline access is blocked, achieving repeatable chamber measurements accurate to within 0.001 inches using this reloading overall length gauge.
• Target reloaders monitoring barrel throat erosion over time — Need to track chamber wear across extended firing schedules, using this overall length gauge to detect forward land migration to within 0.001 inches of travel.

Less suitable for: Reloaders working with short-bodied cartridges such as the .17 Hornet and .22 Hornet, or applications requiring Adapter D, which are physically incompatible with this tool; and shooters loading exclusively for bolt-action and single-shot rifles with open rear access, where a straight-bodied OAL gauge provides a more direct, user-friendly inline feel.