Reliable 338 Lapua Magnum reloading data can be found in official manufacturer manuals and online databases published by industry leaders such as Hodgdon, Vihtavuori, Nosler, and Sierra. Published data typically covers projectile weights from 200 grains up to 300 grains, detailing starting and maximum powder charges, muzzle velocities, chamber pressures up to SAAMI maximum limits of 69,275 PSI, cartridge overall length, and test barrel specifications. Because the 338 Lapua Magnum is an ultra-high-pressure long-range precision cartridge, minor component variations in large rifle magnum primer selection, powder burn rates, seating depth, and brass neck tension can significantly alter pressure profiles and velocity outcomes.
338 Lapua Magnum Reloading Data Overview
| Bullet Style | Bullet Weight | Powder | Published Starting Load | Published Maximum Load | Published Velocity | Barrel Length / Firearm | Source |
| Barnes TTSX | 225 gr | Hodgdon H-1000 | 82.0 gr | 89.0 gr | 2,950 to 3,120 fps | 27″ / Modern Bolt Action | Hodgdon / Barnes |
| Nosler AccuBond | 250 gr | Vihtavuori N570 | 85.0 gr | 92.5 gr | 2,800 to 2,980 fps | 27″ / Precision Rifle | Vihtavuori / Nosler |
| Hornady ELD-X | 270 gr | Alliant Reloder 33 | 88.0 gr | 96.0 gr | 2,750 to 2,925 fps | 27″ / Custom Match Rig | Alliant / Hornady |
| Berger Hybrid Target | 300 gr | Vihtavuori N570 | 80.0 gr | 87.5 gr | 2,700 to 2,860 fps | 27″ / Precision Rig | Berger / Vihtavuori |
| Sierra HPBT MatchKing | 300 gr | Hodgdon Retumbo | 76.0 gr | 84.0 gr | 2,650 to 2,825 fps | 27″ / Test Barrel | Hodgdon / Sierra |
Understanding The 338 Lapua Magnum Reloading Data
Working up 338 Lapua Magnum load data requires rigorous technical discipline due to the massive powder charges and extreme energy output of the cartridge:
- Starting Load: The conservative minimum charge weight recommended by testing laboratories to ensure clean propellant ignition and consistent pressure development.
- Published Maximum Load: The absolute peak pressure threshold established by testing facilities, rated around 69,275 PSI. Exceeding this value can cause severe overpressure events and premature brass failure.
- Velocity: Quantified in feet per second at the muzzle, reflecting the cartridge’s efficiency in driving heavy, high-BC projectiles across extreme distances.
- Pressure: Measured in PSI. SAAMI establishes a Maximum Average Pressure limit of 69,275 PSI for the 338 Lapua Magnum.
- Case Efficiency: Designed for military and extreme long-range target applications, the large case capacity requires slow-burning double-base or extruded powders to achieve optimal velocity without pressure spikes.
338 Lapua Magnum Bullet Weight Options
Published load data spans several distinct projectile weight classes tailored for tactical applications, long-range match competition, and heavy big-game hunting:
- 200 to 225 Grain: High-velocity options designed for flat trajectories, delivering blistering muzzle speeds exceeding 2,950 to 3,120 fps for lighter game or medium-range targets.
- 250 to 270 Grain: The versatile standard sweet spot for long-range tactical shooting, balancing high ballistic coefficients, manageable recoil, and deep terminal penetration.
- 300 Grain: Heavy-for-caliber ultra-high-BC match and hunting projectiles (such as the Sierra MatchKing or Berger Hybrid), providing exceptional resistance to crosswinds and retained energy at extreme yardage past 1,000 yards.
338 Lapua Magnum Powder Reloading Data
Selecting the correct propellant involves matching slow-burning rifle powders that efficiently fill large-capacity cases while maintaining controlled burn rates:
| Powder | Bullet | Bullet Weight | Published Starting Load | Published Maximum Load | Published Velocity | Source |
| Hodgdon H-1000 | Barnes TTSX | 225 gr | 82.0 gr | 89.0 gr | 2,950 to 3,120 fps | Hodgdon |
| Vihtavuori N570 | Nosler AccuBond | 250 gr | 85.0 gr | 3,250 to 2,980 fps | 2,800 to 2,980 fps | Vihtavuori |
| Alliant Reloder 33 | Hornady ELD-X | 270 gr | 88.0 gr | 96.0 gr | 2,750 to 2,925 fps | Alliant |
| Vihtavuori N570 | Berger Hybrid | 300 gr | 80.0 gr | 87.5 gr | 2,700 to 2,860 fps | Berger |
| Hodgdon Retumbo | Sierra MatchKing | 300 gr | 76.0 gr | 84.0 gr | 2,650 to 2,825 fps | Hodgdon |
Component And Assembly Best Practices
Because the 338 Lapua Magnum operates at extreme pressure levels, meticulous assembly standards are mandatory:
- Cartridge Overall Length (COL): Standard specifications require an overall length typically set between 3.681 inches and 3.740 inches depending on the bullet profile and magazine box constraints of your rifle platform.
- Primer Selection: Always use Large Rifle Magnum Primers (such as the Federal 215M) to ensure complete, uniform ignition of massive charges of slow-burning powder. Standard primers can lead to hangfires or erratic velocities.
- Neck Tension and Sizing: Using high-quality match-grade sizing dies with bushing inserts ensures consistent neck tension, which is vital for maintaining low standard deviations (SD) in velocity over long distances.
Velocity And Barrel Length Considerations
Manufacturer velocity figures are typically generated using heavy test barrels measuring 27 inches to 30 inches in length. Real-world precision rifles featuring 27-inch barrels achieve full performance, but custom configurations with shorter 24-inch tubes will experience notable velocity reductions. Handloaders should always verify speeds with a physical chronograph.
Pressure And Safety
The 338 Lapua Magnum operates at a high maximum average pressure ceiling of 69,275 PSI. Because it generates substantial recoil and thermal energy, strict safety protocols apply:
- Never exceed published maximum loads, and watch closely for heavy bolt lift or primer cratering.
- Ensure all cases are inspected for internal thinning or head separation after multiple firings due to high working pressures.
- Reduce charges by 10 percent when changing component lots, brass brands, or switching primer types.
Best Sources For 338 Lapua Magnum Data
The top references for reliable data include:
- Hodgdon Online Reloading Center: Features extensive laboratory recipes for slow-burning propellants like H-1000 and Retumbo.
- Vihtavuori Reloading Guide: Provides comprehensive data arrays covering premium powders like N570 and N565 optimized for heavy magnum cartridges.
- Nosler and Sierra Manuals: Offer verified accuracy nodes and ballistic insights for elite match and big-game hunting bullets.
Common 338 Lapua Magnum Reloading Questions
Where can I find 338 Lapua Magnum reloading data?
Reliable data is available through official online portals and print manuals published by Hodgdon, Vihtavuori, Nosler, and Sierra.
What powders are popular for 338 Lapua Magnum?
Top-performing slow-burning propellants include Vihtavuori N570, Hodgdon H-1000, Retumbo, and Alliant Reloder 33.
What bullet weights are supported?
Published data accommodates weights ranging from 200 grains up to heavy 300-grain match and hunting projectiles.
Do I need magnum primers for this cartridge?
Yes. Large Rifle Magnum Primers are strongly recommended to ensure clean, uniform ignition of large powder charges.
What is the max pressure for 338 Lapua Magnum?
SAAMI establishes a maximum average pressure limit of 69,275 PSI for the 338 Lapua Magnum cartridge.