The Redding 42256 Tapered Size Button is a precision-machined steel die accessory engineered to progressively expand cartridge case necks from the inside during sizing. Designed to thread directly onto standard Redding decapping rod assemblies, its elongated, gradual taper eases into the case neck rather than catching on an abrupt step. This smooth entry minimises brass work-hardening, reduces neck stretching, and lowers runout during the resizing cycle, preserving case life and concentricity across repeated firings.

Key Features

• Progressive Taper Profile: Expands cartridge necks smoothly from the interior to prevent uneven neck stretching and reduce shoulder deformation.
• Precision Machined Steel: Crafted from heat-treated, polished steel to resist wear and maintain consistent neck tension.
• Direct Die Integration: Replaces factory expander buttons directly on standard Redding Full-Length Sizing Dies, Neck Sizing Dies, and Type-S Bushing Dies.
• Necking-Up Capability: Allows reloaders to smoothly expand smaller parent cases to .25 calibre without crushing the case mouth or collapsing the shoulder.

Specifications

• Manufacturer Part Number (MPN): 42256
• Calibre Compatibility: .25 Caliber (.257" bullet diameter / nominal .255"–.256" expander sizing)
• Material: Heat-treated, polished machined steel
• Weight: Nominal (<30 g / 1 oz)
• Interface: Standard threaded Redding decapping rod assemblies
• Power Requirements: None (manual reloading accessory)

Who is the Redding 42256 Tapered Size Button for?

• Handloaders reloading .25 calibre cartridges — Requires a nominal .255" to .256" expander sizing diameter to establish consistent internal neck tension for .257" bullet seating in cartridges like the .25-06 Remington and .257 Roberts using this Redding reloading die expander button.
• Reloaders forming wildcats or necking up parent cases — Utilises an elongated taper to progressively expand .224" or 6mm parent brass up to .257" bullet diameter dimensions without crushing the case shoulder.

Less suitable for: Non-Redding reloading dies (incompatible with standard non-threaded decapping pins from other brands without proprietary conversions), or radical case conversions stepping up multiple calibre tiers beyond simple necking up, which require multi-step expanding mandrels or dedicated form and trim dies.