Brass cases Peterson .338 Norma Magnum

Peterson Cartridge .338 Norma Magnum is premium American-made, match-grade brass designed for precision long-range shooting and demanding competition use. The cases are supplied new and unprimed, with Large Rifle Primer pockets.

The .338 Norma Magnum is a modern, beltless magnum cartridge developed around long, high-ballistic-coefficient bullets, particularly projectiles weighing approximately 285–300 grains. Its shorter case compared with the .338 Lapua Magnum allows long bullets to be seated with less intrusion into the powder space while maintaining a practical overall cartridge length.

Peterson manufactures its brass with close dimensional and weight tolerances. Shooters commonly praise Peterson cases for their consistency, strong case heads, uniform primer pockets and long service life when used with properly developed loads.

Key benefits

• Match-grade brass manufactured in the USA
• High dimensional and weight consistency
• Strong, beltless case design
• Uniform Large Rifle Primer pockets
• Approximately 0.080-inch flash hole
• Designed for precision long-range cartridges
• Suitable for long, high-BC .338-calibre bullets
• Supplied new and unprimed
• 50 cases per box
• Reusable through multiple reloading cycles when properly maintained

Product specifications

• Manufacturer: Peterson Cartridge
• Calibre: .338 Norma Magnum
• Product type: new, unprimed cartridge cases
• Primer pocket: Large Rifle Primer – LRP
• Flash-hole diameter: approximately 0.080 in / 2.03 mm
• Case design: rimless, bottleneck, beltless magnum
• Material: cartridge brass
• Quantity: 50 pieces
• Country of manufacture: USA
• Peterson product number: 40020-R
• UPC: 859449006346

Peterson production-lot measurements

Peterson publishes detailed ballistician inspection data for individual production lots. The following values illustrate the exceptionally tight manufacturing tolerances, but minor differences between lots are normal.

Production lot C189

• Inspection date: 23 July 2025
• Quality-control reference: 072125
• Average case weight: 297.7 gr / 19.29 g
• Water capacity: 106.8 gr H₂O / approximately 6.92 cm³
• Shoulder diameter: 0.563 in
• Base diameter: 0.583 in
• Neck-wall thickness: 0.0135 in
• Estimated loaded-neck diameter: 0.365 in
• AMP annealer setting: 0150
• AMP pilot: No. 67

Production lot C184

• Inspection date: 22 July 2025
• Quality-control reference: 061725
• Average case weight: 299.2 gr
• Water capacity: 106.5 gr H₂O
• Shoulder diameter: 0.562 in
• Base diameter: 0.583 in
• Neck-wall thickness: 0.0139 in
• Estimated loaded-neck diameter: 0.366 in
• AMP annealer setting: 0152
• AMP pilot: No. 67

Earlier Peterson lots had slightly greater case weights and correspondingly lower internal capacities. For example, lot C114 averaged 303.4 grains with a capacity of 105.8 grains of water, while lot C107 averaged 304.0 grains with a capacity of 106.0 grains of water. Loads should therefore always be verified and, where necessary, redeveloped when changing the case manufacturer or production lot.

SAAMI and CIP reference dimensions

The following figures are cartridge-standard reference dimensions rather than guaranteed measurements for every individual case:

• Maximum case length: 2.492 in / 63.30 mm
• SAAMI case-length range: 2.472–2.492 in / 62.79–63.30 mm
• Overall cartridge length: 3.556–3.681 in / 90.33–93.50 mm
• Maximum neck diameter: 0.370 in / 9.40 mm
• Shoulder diameter: 0.5709 in / 14.50 mm
• Body diameter near the base: approximately 0.5848 in / 14.85 mm
• Rim diameter: 0.578–0.588 in / 14.68–14.93 mm
• Rim thickness: 0.049–0.060 in / 1.24–1.52 mm
• Maximum bullet diameter: 0.3386 in / 8.60 mm
• Reference groove diameter: 0.338 in / 8.58 mm
• Shoulder angle: 20°30′ per side / 41° included angle
• SAAMI maximum average pressure: 62,500 psi
• CIP maximum pressure: 4,400 bar
• CIP proof pressure: 5,500 bar
• SAAMI test-barrel twist rate: 1:9.25, right-hand
• SAAMI test-barrel length: 24 in
• SAAMI reference performance: 300-grain bullet at 2,670 fps / approximately 814 m/s

What shooters say about Peterson .338 Norma Magnum brass

User feedback frequently highlights the consistency of Peterson brass and its ability to support accurate, repeatable long-range loads. Shooters also appreciate the robust case head and stable primer-pocket dimensions. One reported that the primer pockets still passed a go/no-go inspection after the seventh firing, although actual case life always depends on chamber dimensions, load pressure, sizing method and maintenance.

Some users also mention that Peterson .338 Norma Magnum brass is produced less frequently than more popular calibres, so availability can vary. For shooters who already have an accurate load developed with Peterson cases, maintaining a supply from the same production lot may be especially useful.

Redesigned Peterson case geometry

Peterson introduced its .338 Norma Magnum brass in 2018 and later redesigned the manufacturing tooling for its .300 Norma Magnum and .338 Norma Magnum cases. According to the manufacturer, the updated external dimensions closely follow Norma’s case geometry while retaining Peterson’s characteristically hard and durable case-head construction.

Preparation before first use

Peterson’s current recommendation is to visually inspect each case and lightly chamfer and deburr the case mouth before the first firing. Unnecessary full-length sizing of new brass is generally not required unless measurements or compatibility with the rifle’s chamber indicate otherwise.

Peterson announced in January 2026 that its EZ-Seat technology is being applied to current production. However, production lots C184 and C189 were manufactured in July 2025, so EZ-Seat should not be assumed for every box of .338 Norma Magnum brass. Check the packaging or lot information when this feature is important.

Important information

.338 Norma Magnum and .338 Lapua Magnum cases are different and are not interchangeable. Always use components that match the exact cartridge designation marked on the firearm.

Case capacity and dimensions may vary slightly between manufacturers and production lots. When changing brass, begin load development again using verified reloading data and follow all applicable safety procedures.

Peterson Cartridge .338 Norma Magnum brass is an excellent choice for precision shooters looking for consistent case volume, durable primer pockets and match-grade manufacturing quality in a modern, high-performance long-range cartridge.