The 338 RCM, introduced in 2008, is renowned for its high velocity, flat trajectory, and magnum performance in a short-action rifle. Designed by Ruger and Hornady as a rimless, short-length cartridge based on the 375 Ruger case to deliver powerful ballistics in compact rifles, it excels in big game hunting and long-range shooting. This caliber provides hunters with increased energy and speed, making it ideal for large game such as elk, moose, and bear. In this guide, we explore its technical specs, advantages, reloading tips, and comparisons to similar calibers like the 300 RCM and 338 Winchester Magnum.
Caliber Description
The 338 RCM features a bullet diameter of 0.338 inches, with a case length of 2.100 inches. Bullet weights typically range from 180 to 250 grains, available in various configurations for different applications.
Full Metal Jacket (FMJ): Used for training and target practice, offering consistent performance and minimal expansion.
Hunting (Soft Point, Ballistic Tip, Hollow Point): Designed for controlled expansion and deep penetration on game animals.
Match-Grade: Engineered for precision shooting, with high ballistic coefficients for long-range accuracy.
Common powders include slow-burning types like H1000 for optimal velocity. Muzzle velocities reach up to 2800 fps with 225-grain bullets. Compatible rifles include the Ruger Hawkeye Compact Magnum, Winchester Model 70, Browning X-Bolt, and Savage Model 12.
Advantages: High velocity for flat trajectories; versatile for large game; efficient in short-action rifles.
Disadvantages: Higher recoil than smaller calibers; ammunition can be more expensive and less available; faster barrel wear due to high pressures.
Comparison: Compared to the 300 RCM, the 338 RCM offers more energy for larger game but with increased recoil. Versus the 338 Winchester Magnum, it provides similar performance in a shorter action.
Technical Characteristics
| Characteristic | Value |
|---|---|
| Bullet Diameter (inches) | 0.338 |
| Case Length (inches) | 2.100 |
| Bullet Weight (grains) | 180-250 |
| Muzzle Velocity (fps) | 2800 (225 gr) |
| Muzzle Energy (ft-lbs) | 3920 (225 gr) |
Twist Rate Overview
The 338 RCM typically uses twist rates from 1:9 to 1:12, influencing bullet stabilization based on weight and barrel length. Faster twists like 1:9 suit heavier bullets for long-range stability, while 1:12 works well for standard loads.
| Twist Rate | Optimal Bullet Weight (grains) | Recommended Barrel Length (inches) |
|---|---|---|
| 1:9 | 225-250 | 24-26 |
| 1:10 | 200-225 | 22-24 |
| 1:12 | 180-200 | 20-24 |
Recoil
The 338 RCM generates approximately 35 ft-lbs of recoil energy in an 8-pound rifle, using the formula: recoil energy = (bullet weight * velocity^2) / (2 * gravitational constant * rifle weight). It is manageable for experienced shooters with proper technique.
Recoil Comparison:
Lower Recoil: The 300 RCM produces about 25 ft-lbs, making it milder for extended sessions.
Higher Recoil: The 338 Winchester Magnum delivers around 40 ft-lbs, suitable for larger game but more punishing.
This balance makes the 338 RCM versatile for hunters seeking power without excessive kick.
Recoil Comparison Table
| Caliber | Recoil (ft-lbs) | Rifle Weight (pounds) |
|---|---|---|
| 338 RCM | 35 | 8 |
| 300 RCM | 25 | 8 |
| 338 Winchester Magnum | 40 | 8 |
Caliber Comparison
Compared to the lighter 300 RCM, the 338 RCM offers higher energy and penetration for bigger game but with more recoil. Versus the harder 338 Winchester Magnum, it has a similar trajectory with less kick, though with reduced stopping power on very large animals.
Comparison Table
| Caliber | Bullet Weight (grains) | Muzzle Velocity (fps) | Muzzle Energy (ft-lbs) | Effective Range (yards) |
|---|---|---|---|---|
| 338 RCM | 225 | 2800 | 3920 | 500 |
| 300 RCM | 180 | 2950 | 3478 | 500 |
| 338 Winchester Magnum | 225 | 2800 | 3920 | 600 |
For more details, see 300 RCM vs 300 WSM and Ballistics of 338 Winchester Magnum.
Applications and Practical Use
Hunting: Effective for elk, moose, and bear with 200-250 grain bullets for ethical kills up to 500 yards.
Sport Shooting: Popular for long-range target practice due to flat trajectory.
Military/Self-Defense: Limited use, but viable for home defense in rural areas.
Recommendations:
Hunting: Pair with Nosler Accubond bullets for expansion.
Sport Shooting: Use match-grade loads for precision.
Training: FMJ for cost-effective practice.
Ballistics and Performance
For a 225-grain bullet:
Muzzle Velocity: 2800 fps
Energy: 3920 ft-lbs at muzzle, 2800 at 200 yards
Trajectory Drop: -1.5 inches at 100 yards (zeroed at 200)
Ballistic Coefficient (BC): 0.514
This setup delivers excellent downrange performance. For a deeper analysis, see Ballistics of 338 RCM.
Basic Ballistics Table
| Distance (yards) | Velocity (fps) | Energy (ft-lbs) | Drop (inches) |
|---|---|---|---|
| 0 | 2800 | 3920 | 0 |
| 100 | 2600 | 3380 | -1.5 |
| 200 | 2410 | 2900 | 0 |
| 300 | 2230 | 2480 | -6.5 |
| 400 | 2050 | 2100 | -19 |
| 500 | 1880 | 1760 | -39 |
Note: Data for standard conditions: 59°F, sea level, sight height 1.5 inches, zeroed at 100 yards, 24-inch barrel.
Long-Range Performance
At 1000 yards:
Velocity: 1400 fps
Energy: 980 ft-lbs
Drop: 300 inches
Wind Drift: 80 inches in 10 mph crosswind
Comparable to other .338s but with better retention than smaller calibers.
Factors Affecting Performance
Several elements influence the 338 RCM’s ballistics.
Atmospheric Conditions: Higher altitudes reduce air density, increasing velocity by up to 5%.
Powder Type: Slow-burning powders like H1000 optimize energy transfer.
Barrel Length: Longer barrels (24-26 inches) boost velocity by allowing complete powder burn.
Trajectory Calculation: Use the formula: drop = (gravity * time^2) / 2, adjusted for BC and velocity.
Reloading
Reloading the 338 RCM is economical with widely available components. Follow SAAMI specs for safety, starting low and monitoring pressure signs. This caliber benefits from precise loads for accuracy, with case life extended through annealing. Components are plentiful from brands like Hornady and Norma, allowing customization for hunting or competition. Always use a chronograph to verify velocities and ensure consistency in seating depths for optimal performance. Proper neck tension and primer selection can significantly improve ignition reliability, especially in varying temperatures. Experimenting with different powder charges within safe limits helps achieve sub-MOA groups, making it a favorite among precision reloaders.
Primers and Cases
Primers: Large Rifle Magnum primers are common for reliable ignition in cold weather or heavy charges. Standard Large Rifle work for lighter loads.
Cases: Brass from Hornady or Norma, with headstamps indicating manufacturer. Capacities around 72 grains of water.
| Component Type | Common Brands/Markings | Suitable For |
|---|---|---|
| Primer | CCI 250, Federal 215 | Magnum loads |
| Primer | Winchester WLRM | Standard loads |
| Case | Hornady | All applications |
| Case | Norma | Precision reloading |
Bullets
Popular bullets include options for precision and expansion. Heavier weights for big game, lighter for varmints.
| Bullet Brand/Model | Weight (grains) | Type | Best For |
|---|---|---|---|
| Nosler Accubond | 225 | Bonded | Hunting |
| Berger VLD | 230 | HPBT | Long-range |
| Hornady ELD-X | 230 | Polymer Tip | Precision hunting |
| Sierra GameKing | 225 | SP | General use |
Powders
Suitable powders provide consistent burns for velocity. Examples include:
| Powder Brand/Marking | Suitable Bullet Weights (grains) | Best For |
|---|---|---|
| Hodgdon H1000 | 225-250 | Accuracy |
| IMR 4350 | 200-225 | High velocity |
| Alliant Reloder 22 | 225-250 | General hunting |
| Hodgdon Retumbo | 230-250 | Heavy loads |
| IMR 4831 | 200-230 | Precision |
| Vihtavuori N560 | 225 | Long-range |
| Ramshot Magnum | 200-225 | Versatile |
| Accurate Magpro | 225-230 | Magnum performance |
| Alliant Reloder 25 | 230-250 | Short magnums |
| Hodgdon H4831 | 200-225 | Target |
| IMR 7977 | 225 | Heavy bullets |
| Norma MRP | 200-250 | Extreme weather |
Practical Considerations
Barrel Wear: High pressures lead to faster throat erosion; clean regularly and monitor for accuracy loss.
Optics and Setup: Use scopes like Vortex Viper or Leupold VX-5HD with 3-18x magnification for versatile ranging.
Conclusion
The 338 RCM stands out for its versatility, delivering high velocity and energy in a compact package. While it excels in hunting and sport shooting, consider its recoil and ammo costs. Ideal for experienced reloaders, it remains relevant for future big game pursuits. Explore related guides like How to Choose the Perfect Caliber for Big Game Hunting in 2026 and Long-Range Hunting Calibers Explained.
