Modular Sizing Die – GT

After studying precision CNC machines and tooling, we designed the Modular Sizing Die to use a series of shallow tapers instead of threads to properly center and secure the Solid Decapping Pin. This tapered geometry ensures unparalleled concentricity and repeatability.

Finally, we designed the cartridge sizing geometry to size a little more at the base and a little less at the shoulder compared to most resizing dies on the market. In properly sized rifle chambers, this design helps eliminate extraction issues with fired brass. Our shoulder sizing geometry minimizes case runout and prevents overworking the brass by avoiding excessive shoulder sizing.

Modular Sizing Die Assembly

• Modular Sizing Die Body: Features standard 7/8 x 14 threads, constructed from 17-4 Stainless Steel, with a special Salt Bath Nitride finish that enhances lubricity and performance compared to other resizing dies on the market.
• Universal Solid Decapping Pin: Made from high-strength 1144 Stress Proof Steel. The .058” nominal diameter pin tip fits small primer flash-holes. You can set the Solid Decapping Pin to any pin tip protrusion by adjusting the wide mouth retaining clip’s position.
• Knurled ER11 Top Cap: Tightens into the die body with ¾ x 24 threads, compressing the supplied ER11 collet to securely hold the Decapping Pin or Expander Mandrel, ensuring maximum concentricity.
• ER11 Collet: A commercially available ER11 collet that secures a variety of Decapping Pin and Expander Mandrel diameters.
• Taper Adapter: When you thread the Knurled ER11 Top Cap into the die body, it seats the ER11 Collet into the Taper Adapter, securing the Decapping Pin or Expander Mandrel. The Taper Adapter sits directly above the Neck / Shoulder Sizing Bushing, allowing it to float.
• Neck / Shoulder Bushings: Available in various caliber-specific neck diameters. You can place special .001” shims above the Neck/Shoulder Bushing to adjust headspace without threading the die in or out, similar to traditional dies.

To set up your Short Action Customs Modular Sizing Die, please follow these steps

• Ensure the inside of the resizing die is clean and free of debris. We recommend using a .40 caliber plastic pistol brush with a 12 gauge shotgun patch to clean the inside of the die body.
• Assemble your Modular die similarly to the picture below.
• With the reloading press ram fully raised, thread the resizing die into the top of the reloading press until the die body touches the shell holder. Then, lower the ram and thread the die down slightly to achieve a little “cam over” with the press. Tighten the die body lock ring. If you’re using the Area 419 Zero Press, we recommend threading in your die approximately 1/8″ of a turn after the die touches the shell holder.
• Use a headspace comparator that contacts the shoulder of the brass to establish the fired brass headspace.
• Next, lubricate a piece of clean, fired brass and cycle it through the Modular Sizing Die with a smooth, consistent ram stroke.
• Measure your sized brass and compare it to the fired brass. We recommend reducing the headspace of the fired brass by .001”-.003” for most shooting applications.
• To increase or decrease sized brass headspace, thread the resizing die body further into the press or less. Using Redding Competition Shell Holders is also recommended. Another way to adjust headspace is to remove or install custom .001″ shims supplied with your die between the “Neck/Shoulder Bushing” and the “Taper Adapter.”

What’s in the package

• Modular Sizing Die Body
• Standard orange or grey lock ring
• ER11 Top Cap
• Taper Adapter
• ER11 Collet
• Decapping Pin
• (4) .001″ Shims
• Cardboard Shipping box