The Hornady Lock-N-Load® Modified Case – 7mm Remington Ultra Magnum (MPN: B7MM) is a dedicated measuring tool designed to establish exact overall cartridge length and bullet jump to the rifling lands. Manufactured to factory SAAMI chamber specifications with a case length of 2.850 in (72.4 mm), this non-powered reloading accessory works alongside Hornady Straight (C1000) and Curved (C1550) O.A.L. Gauges. It allows precision handloaders to seat standard .284-calibre projectiles by hand into the chamber to obtain accurate, repeatable dimensional data.

Key Features

• Direct Tool Interface: Features a factory-drilled and tapped 5/16"-36 threaded case-head to attach directly to Hornady Lock-N-Load O.A.L. Gauges.
• Precision Slip-Fit Neck: The case neck is manufactured .002" (.051 mm) over standard SAAMI specifications, allowing free insertion and extraction of .284" bullets without neck tension.
• Repeatable Accuracy: Enables seating-to-lands measurements repeatable within .001" (.025 mm) when used with a caliper and bullet comparator.
• Mechanical Construction: Purely mechanical brass casing requiring no electrical power or compliance certifications for standard workshop use.

Specifications

• Product Name: Hornady Lock-N-Load® Modified Case – 7mm Remington Ultra Magnum
• Model Number: B7MM
• Calibre Compatibility: 7mm Remington Ultra Magnum (7mm RUM)
• Compatible Projectile Diameter: .284 in
• Thread Pitch: 5/16"-36
• Neck Modification: +.002 in (+0.051 mm) over SAAMI diameter
• Nominal Case Length: 2.850 in (72.4 mm)
• Repeatability: Within .001 in (.025 mm)

Who is the Hornady Lock-N-Load Modified Case for 7mm Remington Ultra Mag for?

• Handloaders Reloading for 7mm Remington Ultra Magnum Rifles — Requires a 5/16"-36 threaded case-head and an oversized neck opened by .002" to gauge seating depth for .284-calibre projectiles within a SAAMI-spec 7mm RUM chamber.
• Long-Range Precision Shooters Optimizing Bullet Jump for 7mm RUM — Delivers measurement repeatability to within .001" (.025 mm) when determining the exact distance to the rifling lands using this modified case with an O.A.L. gauge.

Less suitable for: Standard 7mm Remington Magnum or 7mm Rem SAUM chambers, as well as custom-chambered rifles where fire-forming significantly alters chamber headspace and diameter; these applications require a calibre-specific factory case or a custom-modified case drilled and tapped from the rifle's own fire-formed brass.