Lyman H&i Sizing Die .377

• Precision bullet sizing: The .377 sizing diameter helps bring cast bullets to a consistent finished size, which supports better fit in the bore and more uniform on-target results.
• Built for cast-bullet lubrication: As part of Lyman’s H&I sizing die system, this die is made for use in bullet sizing and lubrication setups, helping streamline cast-bullet finishing in one workflow.
• Hardened steel construction: The steel body stands up to repeated shop use and helps maintain dimensional consistency over time, which matters when processing batches of bullets.
• Tapered, alignment-friendly design: Lyman’s H&I sizing dies use a tapered mouth and hardened interior to guide bullets into the die more smoothly and help preserve a uniform cylindrical shape.
• Standard press compatibility: The 7/8"-14 thread format fits standard reloading press setups, making it easier to integrate this die into an established casting and reloading bench.

About the H&I Series

Lyman H&I sizing dies are part of the company’s long-established cast-bullet reloading range, aimed at reloaders who want to control bullet diameter and lubrication as part of a complete bullet-casting workflow. These dies are used with Lyman lube-sizing equipment to size cast bullets to the desired diameter while supporting proper lubricant application, an important step for shooters working with handgun and rifle cast loads.

The series is built around practical shop use. Improved 90° hole spacing is intended to make bullet lubrication easier, including with harder lubricants, while the tapered mouth and hardened interior help guide bullets into the die and maintain a consistent cylindrical form. Lyman also matches the interior dimensions of these dies to commonly recommended bullet diameters for popular calibers, so the H&I line serves as a straightforward sizing solution for reloaders who tune cast bullets for fit, function and accuracy. The dies are also noted as interchangeable with RCBS, which adds flexibility for reloaders already using compatible equipment.

About the Lyman H&i Sizing Die .377

The Lyman H&i Sizing Die .377 is a single standard body-sizing die made for cast bullets that need to be brought to a .377 / 9.58 mm finished diameter. In practical terms, that makes it a useful tool for reloaders who cast their own bullets and want tighter control over bullet fit before loading. Proper bullet diameter is a key part of cast-bullet performance, affecting how the bullet seals in the bore, how consistently it travels down the barrel and how cleanly it can be shot.

This die uses a steel sizing body and a standard 7/8"-14 thread, so it fits easily into common reloading setups. As part of Lyman’s H&I system, it is intended for bullet sizing rather than case sizing, and it supports the bullet-finishing stage where dimensional consistency matters most. The die’s form is designed to help bullets enter smoothly and stay aligned during sizing, which is especially useful when processing larger batches and trying to keep results uniform from one bullet to the next.

For cast-bullet shooters, the value of this model is straightforward: it gives a repeatable way to size bullets to a specific diameter, helping create ammunition that is better matched to the firearm and more consistent in use. Made in the USA, it suits reloaders who want a durable, bench-ready bullet sizing die for regular workshop use.

About Lyman

The Lyman Gun Sight Company began in 1878 in Middlefield, Connecticut, giving the brand a long history in shooting equipment. Lyman makes equipment and accessories for shooting and reloading, with product lines that include reloading dies, presses, bullet-casting equipment, and gun sights. That background is especially relevant in products like bullet sizing dies, where practical bench experience and long-term familiarity with reloading tools matter.

Lyman Products is headquartered in Middletown, Connecticut, and the company’s reloading heritage was strengthened when it acquired the Ideal reloading-tool business in 1925. Over time, Lyman expanded further within the shooting market, including the addition of Pachmayr in 1996. The result is a manufacturer known for traditional shooting accessories as well as established reloading equipment for handloaders and cast-bullet shooters.

Main Features

• Manufacturer: Lyman
• Made in: USA
• 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: 9.58 mm
• Bullet diameter: 377.00 inch

Warranty

Lyman provides a 2-year warranty for this product. This stated warranty period covers defects in material and workmanship under the manufacturer’s warranty terms.