The Sellier & Bellot .357 Magnum Unprimed Brass Cases (50 Pack) are reloadable cartridge components engineered for handloading and custom ammunition manufacturing. Manufactured from drawn Cu-Zn alloy brass in Vlašim, Czech Republic, each factory-annealed case is designed to withstand standard magnum operating pressures without premature case-mouth splitting. Featuring a nominal case length of 1.290 in (32.77 mm) and a standard Boxer primer pocket, these cases provide a uniform foundation for building accurate, reliable rounds for revolvers and pistol-calibre carbines.

Key Features

• Factory-Annealed Construction: Drawn reloading brass features annealed necks and case walls to optimise ductility, improve brass lifespan, and handle repetitive cycling.
• Boxer Primer Compatibility: Drilled with standard Boxer flash holes compatible with standard Small Pistol and Small Pistol Magnum primers, enabling easy depriming and re-priming using conventional reloading dies.
• Standard SAAMI/CIP Dimensions: Machined to industry specifications with a nominal case length of 1.290 in (32.77 mm) and a rim diameter of approximately 0.440 in (11.18 mm).
• Pressure Resilience: Engineered to safely operate up to SAAMI maximum average pressure (MAP) thresholds of 35,000 psi (or CIP Pmax of 3,000 bar / 43,511 psi).

Specifications

• Brand: Sellier & Bellot
• Manufacturer Part Number: V316402
• Calibre: .357 Remington Magnum
• Quantity: 50 pieces per pack
• Material: Drawn Cu-Zn brass alloy (factory annealed)
• Primer Pocket: Small Pistol / Small Pistol Magnum (Boxer)
• Nominal Case Length: 1.290 in (32.77 mm)
• Nominal Rim Diameter: 0.440 in (11.18 mm)
• Pressure Rating: SAAMI MAP of 35,000 psi (CIP Pmax: 3,000 bar / 43,511 psi)
• Weight: Approximately 5.3 g per unprimed case (~265 g per 50-pack)
• Preparation Required: Must be full-length resized, chamfered, and inspected prior to initial charging

Who is the S&B Sellier & Bellot 357 Mag Unprimed Brass Cases 50 Pk for?

• Revolver handloaders — requires unprimed pistol brass built with standard Boxer primer pockets to seat Small Pistol or Small Pistol Magnum primers safely under SAAMI maximum average pressures of up to 35,000 psi.
• Pistol-calibre lever-action shooters — relies on the standard 1.290 in (32.77 mm) nominal case length and 0.440 in (11.18 mm) rim diameter to ensure smooth cycling and feeding in tubular magazines and carbine actions.
• Metallic silhouette competitors — utilizes 50-piece packs of drawn, factory-annealed .357 Magnum brass to maintain consistent case volume and mouth ductility across repetitive high-pressure loadings.

Less suitable for: Firearms chambered strictly in standard .38 Special, as this .357 Magnum brass is 0.135 in longer and must never be chambered or forced into .38 Special chambers; handloaders should use dedicated .38 Special brass cases instead. It is also less suitable for target engagements beyond 150 to 200 m, where dedicated bottleneck rifle calibres suit better.