The 7mm Remington Magnum, introduced by Remington in 1962 alongside the iconic Model 700 rifle, is one of the most successful and popular belted magnum cartridges in modern shooting history! Developed by necking down the legendary 375 H&H Magnum case and shortening it to fit standard long-action receivers, it fires aerodynamic 284-thousandths-inch projectiles at blistering velocities. By combining an expansive powder capacity with flat trajectories and manageable recoil, the 7mm Remington Magnum became an instant favorite for big-game hunters and long-range shooters worldwide.
7mm Remington Magnum Case Dimensions Overview
| Dimension Property | Specification (Imperial) | Specification (Metric) |
| Parent Case | 375 H&H Magnum | 375 H&H Magnum |
| Bullet Diameter | 284 thousandths in | 7 mm and 21 hundredths |
| Case Length | 2 inches and 500 thousandths | 63 mm and 50 hundredths |
| Case Trim Length | 2 inches and 490 thousandths | 63 mm and 25 hundredths |
| Overall Length (COAL) | 3 inches and 290 thousandths (Max) | 83 mm and 57 hundredths |
| Rim Diameter | 532 thousandths in | 13 mm and 51 hundredths |
| Rim Thickness | 50 thousandths in | 1 mm and 27 hundredths |
| Base Diameter | 513 thousandths in | 13 mm and 3 hundredths |
| Shoulder Diameter | 488 thousandths in | 12 mm and 40 hundredths |
| Neck Diameter | 315 thousandths in | 8 mm |
| Shoulder Angle | 25 degrees | 25 degrees |
| Case Capacity | Approx 79 grains water | 5 cubic cm and 16 hundredths |
| Maximum Average Pressure | 61-thousand psi | 421 megapascals |
Understanding the 7mm Remington Magnum Case Dimensions
- Belted Lineage: Inherits its distinctive external belt from the classic 375 H&H Magnum parent lineage, a design historically utilized for headspacing on early magnums;
- Magnum Powder Capacity: Features an elongated body and generous internal volume designed to hold slow-burning propellants necessary for high-velocity performance;
- High-BC Optimization: Configured specifically to seat sleek, aerodynamic 7mm projectiles that retain exceptional velocity and energy at extended distances;
- Long-Action Compatibility: Built with a maximum overall length of 3 inches and 290 thousandths, requiring a standard long-action receiver and internal magazine box.
7mm Remington Magnum Case Dimensions in Inches and Millimeters
| Measurement Point | Max (Inches) | Min (Inches) | Max (Millimeters) | Min (Millimeters) |
| Case Length | 2 and 500 thousandths | 2 and 450 thousandths | 63 and 50 hundredths | 62 and 23 hundredths |
| Trim-To Length | 2 and 490 thousandths | None | 63 and 25 hundredths | None |
| Rim Diameter | 532 thousandths | 522 thousandths | 13 and 51 hundredths | 13 and 26 hundredths |
| Base Diameter | 513 thousandths | 508 thousandths | 13 and 3 hundredths | 12 and 90 hundredths |
| Shoulder Diameter | 488 thousandths | 482 thousandths | 12 and 40 hundredths | 12 and 24 hundredths |
| Neck Diameter | 315 thousandths | 309 thousandths | 8 mm | 7 and 85 hundredths |
| Bullet Diameter | 284 thousandths | 282 thousandths | 7 and 21 hundredths | 7 and 16 hundredths |
| Overall Length (COAL) | 3 and 290 thousandths | 3 and 150 thousandths | 83 and 57 hundredths | 80 mm |
7mm Remington Magnum Case Length and Trim Specifications
The maximum case length of the 7mm Remington Magnum is 2 inches and 500 thousandths (63 mm and 50 hundredths), with a recommended trim-to length of 2 inches and 490 thousandths (63 mm and 25 hundredths)! Because it operates at a high maximum pressure limit of 61-thousand psi, brass stretching frequently occurs over repeated high-velocity firing cycles. Handloaders must regularly measure and trim cases to maintain consistent neck tension and prevent chambering issues.
7mm Remington Magnum Belted Base and Rim Dimensions
The 7mm Remington Magnum features the prominent belt and rim architecture characteristic of traditional H&H-derived magnums:
- Rim Diameter: 532 thousandths in (13 mm and 51 hundredths)
- Base Diameter: 513 thousandths in (13 mm and 3 hundredths)
- Rim Thickness: 50 thousandths in (1 mm and 27 hundredths)
While modern reloading practices rely on the shoulder datum for headspacing, the external belt remains a defining structural feature that ensures positive extraction and robust rim strength under heavy bolt thrust.
7mm Remington Magnum Shoulder and Neck Dimensions
- Shoulder Angle: Features a standard 25-degree shoulder angle that balances smooth feeding characteristics with efficient powder containment;
- Shoulder Diameter: Measures 488 thousandths in where the case body transitions upward toward the neck slope;
- Neck Length & Diameter: Provides a neck diameter of 315 thousandths in, engineered to securely grip heavy, high-BC long-range hunting bullets.
7mm Remington Magnum Case Capacity and Pressure
The internal case capacity of the 7mm Remington Magnum averages approximately 79 grains of water, providing an abundant volume of powder space. This capacity works exceptionally well with slow-burning rifle propellants like Hodgdon H1000, Retumbo, and IMR 7828, driving heavy 150-grain to 175-grain bullets to muzzle velocities near 3-thousand feet per second while remaining safely at or below 61-thousand psi.
7mm Remington Magnum Dimensions vs Similar Cartridges
| Cartridge | Bullet Diameter | Case Length | COAL | Max Pressure |
| 7mm Remington Magnum | 284 thousandths | 2 and 500 thousandths | 3 and 290 thousandths | 61-thousand psi |
| 280 Remington | 284 thousandths | 2 and 540 thousandths | 3 and 300 thousandths | 60-thousand psi |
| 280 Ackley Improved | 284 thousandths | 2 and 525 thousandths | 3 and 330 thousandths | 65-thousand psi |
| 300 Winchester Magnum | 308 thousandths | 2 and 620 thousandths | 3 and 340 thousandths | 64-thousand psi |
| 30-06 Springfield | 308 thousandths | 2 and 494 thousandths | 3 and 340 thousandths | 60-thousand psi |
Chamber and Case Dimensions
Chamber specifications for the 7mm Remington Magnum are designed to accommodate long, aerodynamic match and hunting bullets without sacrificing internal powder volume. Because factory chambers often feature generous freebore lengths to ensure smooth feeding, handloaders frequently tune their seating depths closer to the lands to maximize precision during long-range engagement.
Common Questions
- What is the purpose of the belt on 7mm Remington Magnum brass?The belt was originally designed to allow the cartridge to headspace off the belt ledge, a convention carried over from its 375 H&H Magnum parentage. In modern firearms, most precision rifles and sizing dies utilize the shoulder datum for headspacing instead.
- What is the standard twist rate for 7mm Remington Magnum dimensions?A traditional 1 in 9 and a half or 1 in 10 twist rate is standard for factory barrels, effectively stabilizing traditional hunting bullets up to 160 grains, while modern custom builds often prefer a faster 1 in 8 twist rate for ultra-heavy long-range projectiles!
- Can I form 7mm Remington Magnum brass from other cases?While it is technically possible to form belted magnum brass from larger parent cases, factory-formed brass is widely available and affordable, making custom case forming rare for this specific cartridge.