The Hornady Custom Grade New Dimension (CGND) Seating Die for .300 Remington Ultra Magnum (MPN: 044159) is a dedicated reloading die designed to seat and align .308 in (7.62 mm) rifle bullets into .300 RUM cartridge cases. Built with industry-standard 7/8"-14 threads, it mounts directly to standard single-stage, turret, or progressive reloading presses. It features an internal floating bullet alignment sleeve that holds the case neck and projectile in alignment before seating begins, substantially reducing bullet run-out and concentricity errors. Packaged shipping dimensions are approximately 175 mm (L) × 32 mm (W) × 32 mm (H) with a weight of approximately 0.29 kg.

Key Features

• Floating Alignment Sleeve: Pre-aligns the .308 in bullet and .300 RUM case neck before the seating stem engages, minimizing concentricity issues during bullet seating.
• Adjustable Roll Crimp: Integrated roll crimp profile allows reloaders to apply a crimp into bullet cannelures or back the die off to perform seating-only operations.
• Sure-Loc Lock Ring: Uses a split-ring clamp design with a cross-bolt to secure the 7/8"-14 thread positioning without damaging die threads.
• Modular Compatibility: Works with aftermarket upgrades such as the Hornady MicroJust micrometer stem for 0.001 in adjustments, as well as dedicated VLD seating stems.

Specifications

• Cartridge Compatibility: .300 Remington Ultra Magnum (.300 RUM)
• Bullet Diameter: .308 in (7.62 mm)
• Thread Interface: 7/8"-14 thread
• Operation Type: Manual mechanical seating die
• Packaged Dimensions: 175 mm (L) × 32 mm (W) × 32 mm (H)
• Packaged Weight: 0.29 kg (0.64 lb)
• Shellholder Requirement: Compatible .300 RUM shellholder (e.g., Hornady #5)

Who is the Hornady Custom Grade .300 RUM Seating Die for?

• Long-Range Hunting Handloaders — who require straight, concentric hunting cartridges for .300 RUM rifles, utilizing the 7/8"-14 thread press interface and an in-line floating sleeve that seats .308 in diameter hunting projectiles precisely into the neck.
• Match-Grade Target Reloaders — who need to minimize bullet run-out when assembling rounds using .308 in match bullets, relying on the internal alignment sleeve to hold tight concentricity tolerances on large-capacity .300 Remington Ultra Magnum cases.

Less suitable for: Reloaders needing to resize fired brass cases or loaders working with other .30 calibre cartridges like .300 Win Mag or .300 WSM; this tool is strictly limited to the .300 RUM case body geometry and provides bullet seating only, making a dedicated full-length or neck sizing die necessary for case preparation.