The Mighty Armory Gold Match 6mm ARC sizing and decapping die returns fired brass to true SAAMI specification from the case head to the neck with precise die adjustment.

Offering full-length headspace and concentric sizing to SAAMI spec with a simple turn of the die up or down on your reloading press.

Designed for precision rifle shooters running 6mm ARC in AR platforms and bolt guns who demand smooth feeding, controlled headspace, uniform neck tension, and repeatable performance across temperature and load changes.

Why Full Length Sizing Matters for 6mm ARC

6mm ARC is commonly loaded for precision AR platforms and bolt-action rifles where tight chamber fit, consistent shoulder position, and uniform neck tension directly affect reliability and velocity spread. Fired 6mm ARC brass expands at the base and shoulder depending on chamber dimensions, pressure, and firing conditions. Without proper resizing, reloaders may encounter:

• Tight chambering in AR platforms
• Feeding issues under heat and fouling
• Pressure inconsistency across load batches
• Premature brass fatigue
• Larger SD/ES values

The Gold Match 6mm ARC sizing die is engineered to bring fired brass back to SAAMI spec geometry from the case head through the shoulder and neck, ensuring reliable chambering and consistent bullet release for precision work.

Full Length Sizing to SAAMI Specification

The 6mm ARC sizing die features an extended, full length sizing profile that restores cases to SAAMI measurements while preventing under-sizing at the base and over-working the neck and shoulder. SAAMI spec resizing provides:

• Predictable chamber fit
• More consistent case pressure
• Cleaner, more efficient powder burn
• Reliable feeding and extraction
• Improved brass longevity

Full length sizing is recommended for all rifle cases, particularly for 6mm ARC used in AR platforms where reliable chambering is critical. Neck sizing alone does not correct base expansion or chamber-specific deformation and often leads to feeding problems over time.

Precision Machined High Grade Steel to Tight Tolerances

Mighty Armory Gold Match rifle sizing dies are precision machined from high grade tool steel to tight tolerances to ensure repeatable, uniform sizing and consistent concentricity and perfect vertical alignment.

Each 6mm ARC sizing die features:

• True vertical alignment
• Single-point cut internal geometry
• Extremely smooth 5-bore finish
• Heat treated to approximately 60 Rockwell hardness

The extended sizing geometry maintains uniform case shape from head to neck. Concentricity is held to approximately -.0005 at the case mouth and shoulder radius, promoting consistent bullet alignment and repeatable accuracy.

The reloading die is machined with a single point cut finish, which results in an extremely smooth sizing bore at 60 Rockwell hardness.  A hard, smooth sizing surface that is consistent in sizing, especially head-spacing is of the utmost importance when reloading for precision. 

Drop-In Mandrel Expander Shaft

The 6mm ARC sizing die includes a Swiss-machined drop-in 6mm Arc mandrel expander shaft, heat treated to approximately 50 Rockwell for durability. The mandrel expander shaft ensures consistent case mouth expansion for repeatable bullet seating.

The internal threads accept:

• A Mighty Armory decapping pin, or
• A protective pointer that shields threads and helps guide the case into the die

The mandrel shaft seats concentrically within the die bore with three points of contact, ensuring consistent alignment through the sizing stroke and positive lockup with the cap.

Size and Decap in One Pass

The one-and-done sizing of your 6mm ARC brass will be effortless and will easily decap and resize over a million cycles. Adjust the die in your press by turning it up or down to easily set shoulder bump from zero to -.005. The Gold Match 6mm ARC sizing die resizes and decaps in a single operation for efficient case processing.

Included features:

• Primer flicker cap Spring-loaded decapping assembly
• Two .078” diameter decapping pins
• Designed for high-cycle durability

The spring decapping action reduces primer pullback and helps prevent press chute jams. Shoulder bump can be precisely set from zero to approximately -.005” by adjusting the die in your press.

Key Benefits

This 6mm ARC die sizes for Full Length / Shoulder Bump up to -.005 bump. The Mighty Armory FLHS die head space bump is now standard on our FL dies

• True full length resizing with shoulder bump adjustment up to -.005”
• Restores brass to SAAMI specification
• 100% CNC machined in the USA
• Premium heat-treated tool steel
• Smooth 5-bore internal finish
• Concentricity held to -.0005 at mouth and shoulder
• Modular, tool-free serviceability
• Designed for long-term durability

Performance Results

Uniform sizing geometry directly influences:

• Chamber pressure stability
• Cleaner powder combustion
• Reliable chambering and extraction
• Reduced velocity variation (SD/ES)
• Longer brass service life

Sizing with the 6mm ARC Gold Match precision die creates uniform brass geometry — the foundation of consistent, accurate ammunition for competition, training, and hunting.

Learn More

For Single Stage or Turret Presses: We recommend a case sizing wax applied by your fingers.

For Progressive Presses: We recommend PEG75 lanolin spray.

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