Brass cases Peterson .300 PRC

Peterson Cartridge .300 PRC is premium Match-Grade rifle brass designed for shooters who demand excellent consistency from their handloaded ammunition. The cases are manufactured in the United States, subjected to detailed quality-control procedures and supplied new and unprimed.

The .300 PRC, or .300 Precision Rifle Cartridge, was developed by Hornady and accepted by SAAMI in 2018. Peterson Cartridge added it to its product range in response to strong demand from long-range shooters and hunters.

The .300 PRC was designed around long, heavy .30-calibre bullets with high ballistic coefficients. Unlike traditional belted magnum cartridges, it uses a beltless case that headspaces on its 30-degree shoulder. This design supports precise cartridge alignment in the chamber and avoids several limitations associated with conventional belted magnum cases.

Key benefits

• Match-Grade manufacturing quality
• Made in the USA
• Excellent dimensional and internal-capacity consistency
• Large Rifle Primer pocket
• Approximately 0.080-inch / 2.03 mm flash hole
• Strong case-head construction
• Beltless magnum design
• Headspaces on a 30-degree shoulder
• Optimised for long, high-BC bullets
• Suitable for modern barrels with relatively fast twist rates
• Reloadable through multiple firing cycles when properly maintained
• Lot-specific technical data and AMP settings published by Peterson
• 50 cases per box

Product specifications

• Manufacturer: Peterson Cartridge
• Calibre: .300 PRC
• Full cartridge name: .300 Precision Rifle Cartridge
• Product type: new rifle cartridge cases
• Condition: new and unprimed
• Primers included: no
• Primer-pocket type: Large Rifle Primer – LRP
• Flash-hole diameter: approximately 0.080 in / 2.03 mm
• Case type: rimless, bottlenecked and beltless
• Material: cartridge brass
• Manufacturing standard: Match-Grade
• Quantity: 50 pieces
• Country of manufacture: USA
• Peterson product number: 40061-R
• UPC: 810068270105

Latest Peterson production-lot data

Peterson publishes inspection results for individual production lots. These figures show actual production measurements but should not be treated as guaranteed values for every case from every lot.

Lot K189

• Ballistician inspection date: 30 June 2026
• QC number: 061526
• Average empty-case weight: 246.9 gr / approximately 16.00 g
• Average internal capacity: 96.1 gr H₂O / approximately 6.23 cm³
• Shoulder diameter: 0.513 in / approximately 13.03 mm
• Base diameter: 0.529 in / approximately 13.44 mm
• Neck-wall thickness: 0.0133 in / approximately 0.338 mm
• Loaded-neck diameter: 0.336 in / approximately 8.53 mm
• AMP Aztec code: 0144
• AMP pilot: No. 31
• Annealing machine: AMP Mark II

Lot K189B

• Ballistician inspection date: 30 June 2026
• QC number: 061926
• Average empty-case weight: 246.3 gr / approximately 15.96 g
• Average internal capacity: 96.1 gr H₂O / approximately 6.23 cm³
• Shoulder diameter: 0.514 in / approximately 13.06 mm
• Base diameter: 0.529 in / approximately 13.44 mm
• Neck-wall thickness: 0.0130 in / approximately 0.330 mm
• Loaded-neck diameter: 0.335 in / approximately 8.51 mm
• AMP Aztec code: 0141
• AMP pilot: No. 31
• Annealing machine: AMP Mark II

Earlier Peterson production lots had slightly greater case weights and lower internal capacities. For comparison, lot K137 from 2024 averaged 251.7 grains with a capacity of 94.8 grains of water, while lot K088 from 2022 averaged 261.7 grains with a capacity of 93.6 grains of water.

These differences demonstrate why ammunition should be carefully re-evaluated whenever the brass manufacturer or production lot is changed.

SAAMI reference dimensions

The following figures are cartridge-standard reference values and are not measurements of a specific Peterson production lot:

• Maximum case length: 2.580 in / 65.53 mm
• Case-length range: 2.560–2.580 in / 65.02–65.53 mm
• Overall cartridge length: 3.575–3.700 in / 90.81–93.98 mm
• Maximum case-neck diameter: 0.341 in / 8.66 mm
• Shoulder diameter: approximately 0.515 in / 13.08 mm
• Body diameter near the case head: approximately 0.532 in / 13.51 mm
• Rim diameter: approximately 0.522–0.532 in / 13.26–13.51 mm
• Rim thickness: approximately 0.040–0.050 in / 1.02–1.27 mm
• Maximum bullet diameter: 0.3084 in / 7.833 mm
• Reference groove diameter: 0.308 in / 7.82 mm
• Bore diameter: 0.300 in / 7.62 mm
• Shoulder angle: 30°
• SAAMI reference twist rate: 1:8.5, right-hand
• Number of grooves in the test barrel: 6
• SAAMI test-barrel length: 24 in / 609.6 mm
• SAAMI maximum average pressure: 65,000 psi
• CIP maximum pressure, Pmax: 4,400 bar
• CIP proof pressure, PE: 5,500 bar

SAAMI lists a reference velocity of 2,810 fps for a 200-grain bullet and 2,800 fps for a 225-grain bullet. These are cartridge-standard ballistic values and are not performance claims for the brass itself.

Designed around long, heavy bullets

The .300 PRC is based on the .375 Ruger case, necked down to accept a .308-inch bullet. It uses a standard magnum bolt face with a diameter of approximately 0.532 inch.

The maximum overall cartridge length of 3.700 inches allows long, heavy bullets with high ballistic coefficients to be seated without excessive intrusion into the case. This allows the bullet base to remain close to the neck-and-shoulder junction, preserving more usable internal case capacity.

The beltless design also allows cartridges to stack more efficiently in a magazine and can support reliable feeding in rifles correctly designed for the .300 PRC.

Peterson EZ-Seat coating

In January 2026, Peterson announced that its EZ-Seat coating was being applied to all current-production rifle cases. The latest .300 PRC lots, K189 and K189B, were manufactured after this announcement.

EZ-Seat acts as a dry lubricant and anti-tarnish treatment. According to Peterson’s testing, it provides:

• Reduced bullet-seating force
• More consistent seating pressure
• Less bullet-jacket deformation
• More consistent bullet-pull force
• Easier primer seating during the first loading
• Improved protection against tarnishing

The coating is intended primarily for the first loading of new brass. Older inventory may not have the EZ-Seat treatment, so the production-lot number should be checked when this feature is important.

Preparing new cases

Peterson does not recommend extensive preparation of new cases before their first firing. According to the manufacturer’s current guidance, visual inspection and, if necessary, light chamfering and deburring of the case mouth are sufficient.

Full-length sizing of new cases is generally unnecessary if their dimensions are correct and they fit the chamber of the intended rifle. Every additional working cycle contributes to brass fatigue, so unnecessary sizing may reduce service life.

What shooters say about Peterson .300 PRC brass

The benefits most frequently mentioned by shooters include:

• Excellent dimensional consistency
• Uniform neck-wall thickness
• Stable internal capacity
• The potential to achieve low velocity standard deviations
• High manufacturing quality without extensive case sorting
• Strong case heads and durable primer pockets
• Quality frequently compared with Lapua and ADG
• Good repeatability in precision long-range applications

One user working with several Peterson calibres, including .300 PRC brass, reported single-digit velocity SDs and five-shot groups below 0.5 MOA. Another shooter comparing Peterson with Nosler brass found the Peterson cases to be more dimensionally consistent and rated their quality alongside Lapua and ADG.

There are also isolated reports of very tight primer pockets in new Peterson .300 PRC brass. In one case, a user reported considerable resistance when seating several different primer types. This does not appear to affect every production lot, and Peterson states that its current EZ-Seat coating also reduces the force required during initial primer seating.

Important information

.300 PRC cases are not interchangeable with .300 Winchester Magnum, .300 Norma Magnum, .300 Remington Ultra Magnum or other .30-calibre cartridges. Each has different dimensions and requires the correct chamber.

Case capacity can differ between manufacturers and production lots. Switching to Peterson brass or changing to another production lot requires careful re-evaluation using verified data from the manufacturers of the relevant components.

Peterson Cartridge .300 PRC brass is an excellent choice for demanding long-range shooters looking for consistent dimensions, durable construction and Match-Grade quality in a case designed around modern, high-ballistic-coefficient bullets.