The Redding Premium Series Deluxe 3-Die Set (.300 RUM) is a dedicated reloading package engineered for handloading .300 Remington Ultra Magnum ammunition. Built with standard 7/8″-14 threading, this three-die set includes a full-length sizing die equipped with a free-floating carbide expander button, a dedicated neck sizing die, and a bullet seating die fitted with a micrometer-adjustable stem calibrated to 0.001″ increments. The combination allows handloaders to control bullet seating depth, case neck concentricity, and brass working to produce uniform magnum handloads.

Key Features

• Carbide Expander Button: The full-length sizing die features a free-floating carbide size/expander button that reduces friction inside the case neck, minimising brass stretch and runout without requiring internal neck lubricant.
• Micrometer Seating Stem: Features laser-engraved graduations with 0.001″ adjustment increments, allowing repeatable and precise adjustments to cartridge overall length (COAL) and bullet jump.
• Dual Sizing Configuration: Includes both a full-length sizing die for reliable chambering in hunting applications and a neck sizing die to maximise brass life and accuracy in fire-formed brass.
• Heat-Treated Alloy Steel Construction: Precision-machined to tight tolerances, ensuring long-term wear resistance under the high forces required to resize large-capacity magnum cases.

Specifications

• Calibre Compatibility: .300 Remington Ultra Magnum (.300 RUM)
• Thread Pitch: Standard 7/8″-14
• Die Set Composition: Full-Length Sizing Die (with carbide expander), Neck Sizing Die (with steel expander), Bullet Seating Die (with micrometer stem)
• Seating Adjustment Resolution: 0.001″ increments
• Material: Heat-treated alloy steel body with a solid carbide expander button
• Operation: Manual reloading press (mechanical)

Who is the Redding Premium Series Deluxe 3-Die Set for?

• Extreme long-range target shooters using .300 RUM rifles — requires exact bullet jump and seating depth control, achievable through the bullet seating die's micrometer stem calibrated in 0.001″ increments to maintain precise cartridge overall length across high-capacity .300 Remington Ultra Magnum cases.
• Long-range hunters reloading high-capacity .300 RUM magnum ammunition — needs full-length sizing reliability alongside a dedicated neck sizing option that works in standard 7/8″-14 thread pitch presses, preserving fire-formed case dimensions and extending the working life of high-capacity magnum brass.

Less suitable for: Handloaders processing non-RUM .30-calibre cartridges such as .300 Winchester Magnum or .300 WSM, or those reloading cases fired across multiple different rifles, which require a dedicated calibre-specific full-length die set rather than a .300 RUM neck-sizing configuration.