Description
The Hornady Lock-N-Load A Series Modified Case in 300 Blackout is a specially prepared case for use with Hornady’s Lock-N-Load Precision gauges. These modified cases allow handloaders to check and adjust overall cartridge length (OAL), ensuring handloaded ammunition chambers reliably and seats bullets to a precise, repeatable depth.
Each case is threaded at the case-head to thread onto the Lock-N-Load gauge and features a .002″ oversized neck that accepts the same bullet intended to load, so the measurement accurately reflects the actual loaded round. All Hornady Lock-N-Load Modified Cases are manufactured to SAAMI specifications and are readily available to fit the most popular rifle chambers, including the 300 AAC Blackout / 300 Blackout.
An essential reloading accessory for dialing in 300 Blackout handloads, this modified case pairs with the Hornady Lock-N-Load OAL gauge to verify seating depth for accuracy, consistency, and reliable function.








