Lyman H&i Sizing Die .310

• .310 sizing diameter: Brings cast bullets to a consistent final diameter, which helps support better fit in the bore and more uniform downrange performance.
• Body sizing operation: Built specifically for bullet sizing rather than case work, making it a straightforward tool for cast-bullet shooters who want repeatable results.
• 90° hole spacing: The updated die design helps lubricant flow more evenly around the bullet, which is especially useful with harder modern lubes.
• Tapered mouth and hardened interior: Guides bullets into the die more smoothly and helps maintain a true cylindrical shape during sizing.
• Standard 7/8"-14 thread compatibility: Fits common reloading press setups, so it integrates easily into an established casting or bullet-prep bench.

About the H&I Series

Lyman H&I Sizing Dies are part of the company’s long-established cast-bullet and bullet-casting range. They are intended for reloaders who cast their own bullets and need a practical way to bring them to a precise finished diameter while preparing them for lubrication. In Lyman’s lineup, the H&I system sits alongside tools such as the 4500 Lube Sizer, forming a simple and proven approach to cast-bullet preparation for both rifle and pistol use.

The series is built around a straightforward idea: proper bullet diameter is critical to cast-bullet accuracy, consistency and clean handling. Lyman’s improved H&I dies use 90° hole spacing to make lubrication more even, including with harder lubricants commonly used today. A tapered mouth helps start the bullet into the die cleanly, while the hardened interior supports alignment and preserves a uniform cylindrical shape. The range covers many popular diameters, so the H&I series remains a practical choice for reloaders who want dependable, bench-friendly bullet sizing equipment without unnecessary complexity.

About the Lyman H&i Sizing Die .310

The Lyman H&i Sizing Die .310 is a dedicated bullet-sizing die for cast bullets that need a .310 / 7.87 mm finished diameter. In practical use, that makes it relevant for reloaders working with bullet diameters where final fit matters for accuracy, bore sealing and consistent handling during loading. Instead of being a general-purpose die, this is a focused tool for one job: sizing cast bullets to a repeatable dimension before use.

Its steel construction suits regular bench use, while the standard 7/8"-14 thread allows it to fit common press arrangements. That compatibility is important for reloaders who want to add bullet-sizing capability without changing the rest of their setup. As part of Lyman’s H&I design, the die uses 90° hole spacing to support more even lubricant distribution, and the tapered entry helps bullets start straight into the die. The hardened interior is there for a practical reason as well: it helps maintain alignment and preserve bullet shape during sizing. For cast-bullet shooters, those details matter because a uniform finished bullet can contribute to steadier loading results and more predictable performance on the range.

About Lyman

The Lyman Gun Sight Company began in 1878 in Middlefield, Connecticut, establishing the brand early in the American shooting industry. Lyman makes equipment and accessories for shooting and reloading, with product lines that include reloading dies, presses, bullet-casting equipment, and gun sights. That broad focus helps explain why the company remains closely associated with practical tools for handloaders and cast-bullet shooters.

Lyman acquired the Ideal reloading-tool business in 1925, a step that strengthened its place in reloading equipment. Today, Lyman Products is headquartered in Middletown, Connecticut. The brand’s long presence in both sighting equipment and reloading tools gives it particular relevance in categories where mechanical simplicity, repeatability and compatibility with established bench setups still matter.

Main Features

• Manufacturer: Lyman
• Made in: USA
• Product type: Bullet sizing die
• Die operation: Body sizing
• Pack size: Single
• Die type: Standard
• Bushing: No
• Case type: Universal
• Sizing die material: Steel
• Material: Steel
• Adjustment: Standard
• Press compatibility: Standard 7/8"-14 thread
• Bullet diameter: 7.87 mm
• Bullet diameter (inch): 310.00 inch

Warranty

2 years. Lyman states a 2-year warranty for this product, giving clear coverage for manufacturing defects within the stated period.