The Redding .321 Heat-Treated Steel Neck Sizing Bushing (MPN 73321) is a precision reloading component designed to regulate cartridge case neck tension without overworking brass. Featuring an internal diameter of 0.321 inches, it sizes the outside neck diameter of rifle cases to a specific dimension, often eliminating the need for an expander ball. It fits all Redding bushing-style dies—including Type S Neck Sizing Dies, Type S Full Length Sizing Dies, and Competition Neck Sizing Dies—as well as standard Wilson-style neck sizing dies.

Key Features

• Precision Neck Tension Control: Sizes case necks to a fixed 0.321-inch internal dimension, allowing reloaders to precisely set bullet grip and maintain brass longevity.
• Hardened Steel Construction: Manufactured from heat-treated steel hardened to approximately Rockwell C 60–62 (Rc 60–62) for high wear resistance under standard sizing pressures.
• Hand-Polished Sizing Surface: Features hand-polished internal surfaces to reduce friction and brass galling during the resizing stroke.
• Standardised Sizing Footprint: Built with an industry-standard 0.500-inch outer diameter and a 0.375-inch height for broad interchangeability across bushing-compatible reloading dies.
• Clear Identification: Stamped with its 0.321-inch sizing diameter for straightforward identification on the reloading bench.

Product Specifications

• Manufacturer: Redding Reloading Equipment
• Model / MPN: 73321
• Internal Diameter: 0.321 inches
• Outer Diameter: 0.500 inches (1/2 in)
• Height / Length: 0.375 inches (3/8 in)
• Material: Heat-treated steel
• Surface Hardness: Rockwell C 60–62 (Rc 60–62)
• Approximate Weight: 10 to 15 grams
• Die Compatibility: Redding Type S Neck, Type S Full Length, and Competition Bushing Dies; Wilson-style neck sizing dies

Who is the Redding .321 Heat-Treated Steel Neck Sizing Bushing for?

• Precision rifle reloaders tuning cartridge neck tension — Controls bullet grip on brass lots where loaded rounds measure approximately .322 inches to .323 inches, utilising this 0.321-inch steel neck sizing bushing to apply exact 0.001-inch to 0.002-inch neck tension without an expander ball.
• Handloaders processing rifle brass for match or hunting accuracy — Maintains concentricity across standard 0.500-inch outer diameter die systems with a hand-polished Rc 60–62 hardened steel surface that minimises brass fatigue across repeated sizing cycles.

Less suitable for: Loaded cartridge neck diameters outside the .322-inch to .324-inch range, which require an alternative diameter bushing in .001-inch increments between .185 inches and .368 inches; or high-volume brass processing where dry sizing without case lube is preferred, which requires a Titanium Nitride (TiN) coated bushing.