The Hornady Lock-N-Load Cartridge Gauge 40 S&W (Model 380704) is a dedicated handgun cartridge headspace gauge machined from precision steel to SAAMI maximum cartridge tolerances. It allows handloaders to perform an instant go/no-go chamber check on both resized brass and fully assembled .40 S&W ammunition. Rounds dropped into the top of the gauge seat flush and release freely under gravity when they meet factory specification, identifying feeding issues such as case bulges near the web, insufficient crimp, incomplete flare removal, or expanded diameters before live firing.

Key Features

• SAAMI Tolerance Verification: Machined to exact SAAMI maximum cartridge dimensions to confirm that loaded ammunition chambers reliably in standard-spec firearms.
• Complete Geometry Check: Quickly reveals case web bulges, improper taper crimp, excessive case length, and case diameter expansion in a single drop test.
• Dual-Stage Inspection: Functions equally well for checking resized empty cases during press setup and verifying completed .40 S&W rounds prior to competition.
• Precision Steel Construction: Machined from solid steel to maintain bore dimensional integrity over repeated, high-volume workshop use.
• Unpowered Mechanical Operation: Requires no batteries, calibration cables, or power sources, functioning entirely via gravity drop checks.

Specifications

• Manufacturer Model Number: 380704
• Cartridge Compatibility: .40 S&W (.400-inch nominal bullet diameter)
• Capacity: 1 cartridge at a time (single-round inspection)
• Material: Precision-machined steel
• Tolerance Standard: SAAMI maximum cartridge dimensions
• Power Requirements: Unpowered mechanical tool

Who is the Hornady Cartridge Gauge 40 S&W for?

• IPSC, USPSA, and SSAA Practical Pistol Competitors — relies on the SAAMI-spec chamber dimensions of this handgun cartridge headspace gauge to prevent match-stopping malfunctions by ensuring every single competition round loaded for a .40 S&W handgun drops flush and extracts freely.
• High-Volume Handloaders — uses the single-round 1-cartridge capacity port to quickly diagnose setup faults during reloading runs, confirming correct die adjustment, crimp settings, and web sizing on .40 S&W brass before loading large batches.

Less suitable for: High-volume batch processing where checking 1 cartridge at a time creates a bottleneck (a 50-hole or 100-hole multi-cartridge checker block is faster for large batches), or firearms fitted with aftermarket match chambers that feature tolerances tighter than standard SAAMI maximum dimensions (a direct barrel drop test using the disassembled firearm barrel is required for exact match-chamber clearance).