The Redding Competition Seating Die for .243 Winchester Ackley Improved (MPN: 55420) is a dedicated match-grade reloading tool engineered to seat 6 mm (.243 in) bullets with tight concentricity. Designed with a patented internal floating sleeve and seating stem system, the die completely supports and aligns the cartridge case prior to bullet seating to minimise run-out. Built on an industry-standard 7/8"-14 thread, this die integrates directly with standard single-stage and turret reloading presses.

Key Features

• Precision Micrometer Top: Features an infinitely adjustable, non-click micrometer calibrated in 0.001" increments with a zero-reset function for exact cartridge overall length (COAL) indexing.
• Patented Alignment Sleeve: Internal precision-ground sleeve aligns the bullet and case axially before seating begins to eliminate run-out.
• Dedicated Chamber Profile: Specifically dimensioned for fire-formed .243 Winchester Ackley Improved cases with a 40° shoulder angle.
• Match-Grade Design: Built purely for seating precision without an internal crimp ring, preserving consistent neck tension on match brass.

Specifications

• Cartridge Compatibility: .243 Winchester Ackley Improved (40° shoulder angle)
• Bullet Diameter: .243 in / 6 mm
• Thread Standard: 7/8"-14
• Adjustment Graduation: 0.001" increments
• Shellholder Compatibility: Redding #1 Shellholder (#11001) or Redding Competition Shellholder #1 (#11601)
• Shipping Weight: Approx. 0.40 kg
• Crimping Function: None (seating only)

Who is the Redding Competition Seating Die for .243 Winchester Ackley Improved for?

• SSAA target shooting competitors — requires repeatable cartridge overall lengths using the competition seating die's 0.001" increments micrometer adjustments to tune seating depth for match-grade consistency.
• Benchrest and F-Class shooters — relies on the floating sleeve system fitted to 7/8"-14 press threads to align 40° shoulder Ackley Improved cases axially and reduce bullet run-out.
• Long-range varmint and pest hunters — needs precise bullet alignment and seating depth control when handloading high-velocity fire-formed .243 Win Ackley Improved cartridges with a 40° shoulder angle.

Less suitable for: Standard parent .243 Winchester cases without a 40° shoulder angle due to chamber dimension mismatches, which require a standard .243 Winchester seating die; or ultra-long, high-BC projectiles without installing a dedicated VLD profile seating stem (Part #55744) to prevent tip deformation.