Published: January 2026 | Last updated: April 2026
Disclaimer: All load data referenced in this article is drawn from published reloading manuals. The 270 Weatherby Magnum operates at up to 64,000 PSI with large, slow-burning powder charges. Always begin 10% below published maximum charges and work up carefully. Large rifle magnum primers are required. The Weatherby freebore chamber design affects seating depth – do not seat bullets to contact the lands in a Weatherby chamber without specific guidance from your barrel maker.
Roy Weatherby founded his company on a single conviction: higher velocity kills game more cleanly at longer distances. Beginning in the 1940s, he developed a series of high-capacity belted magnum cartridges designed to achieve velocities that contemporary cartridges could not approach. The 270 Weatherby Magnum, introduced in 1943, was among his earliest designs and remains one of the fastest production .277-inch cartridges available.
The 270 Weatherby Magnum pushes a 130-grain bullet at 3,375-3,400 FPS – approximately 300-350 FPS faster than the 270 Winchester and 100-150 FPS faster than the 270 WSM. That velocity advantage at the muzzle translates to more retained energy at long range, a flatter trajectory, and, on Weatherby’s argument, cleaner kills from the increased hydraulic shock of high-velocity impact. Whether you accept Weatherby’s terminal performance theory or not, the ballistic numbers are real.
The trade-offs are also real: belted case construction, Weatherby-specific freebore chamber dimensions, large slow-burning powder charges, and accelerated barrel wear. The 270 Weatherby Magnum is a specialist’s cartridge that rewards shooters who understand its design constraints and build loads accordingly.
Technical Characteristics
| Characteristic | Value |
|---|---|
| Bullet Diameter | 0.277 inches |
| Case Length | 2.549 inches |
| Overall Cartridge Length | 3.295 inches (max) |
| Belted Case Head Diameter | 0.532 inches |
| Case Capacity | ~82-84 grains H2O |
| Case Type | Belted magnum |
| Shoulder Profile | Double-radius (Weatherby proprietary) |
| Max Avg Pressure | ~64,000 PSI |
| Typical Bullet Weight | 100-150 gr |
| Muzzle Velocity (130 gr) | ~3,375-3,400 FPS |
| Muzzle Velocity (140 gr) | ~3,200-3,250 FPS |
| Muzzle Velocity (150 gr) | ~3,050-3,100 FPS |
| Muzzle Energy (130 gr) | ~3,338 ft-lbs |
The Weatherby Freebore Chamber
Every Weatherby cartridge uses a proprietary double-radius shoulder profile and an extended freebore – a section of the barrel ahead of the chamber where the bullet travels before engaging the rifling. This design serves two purposes: it reduces the pressure spike on ignition (allowing higher velocities before reaching maximum pressure), and it provides additional case capacity.
For the reloader, the extended freebore means that standard seating depth recommendations – particularly the practice of seating to 0.010-0.020 inches from the lands – do not apply to Weatherby chambers. Bullets seated to the Weatherby SAAMI specification OAL will jump the freebore before engaging the rifling. This is by design and the cartridge is optimized for it. Do not attempt to seat bullets to contact the lands in a standard Weatherby chamber without measuring your specific chamber’s freebore length.
Belted Case Headspacing
The belt on a Weatherby case headspaces on the belt, not the shoulder. This means the shoulder position is not the primary headspace control. After multiple firings, the shoulder may set back slightly while the belt controls chambering. This is normal for belted cases and does not indicate a problem. However, it does mean that full-length sizing is mandatory for reliable chambering, and the common practice of minimal shoulder bump sizing used in rimless cases is not applicable here.
Twist Rate
| Twist Rate | Optimal Bullet Weight | Barrel Length | Notes |
|---|---|---|---|
| 1:8 | 150-170 gr | 26-28 in | Best for heaviest .277-inch bullets |
| 1:9.5 | 130-150 gr | 24-26 in | Weatherby standard; handles all practical weights |
| 1:10 | 100-140 gr | 22-26 in | Adequate for lighter hunting bullets |
Most Weatherby Mark V rifles use a 1:10 or 1:9.5 twist that handles the standard 130-150 grain hunting load range without issue. The Mark V’s 26-inch barrel is the factory standard and produces the velocity figures in published data. A 24-inch barrel loses approximately 60-80 FPS.
Recoil
At approximately 22-25 ft-lbs in a standard hunting rifle, the 270 Weatherby Magnum is a full magnum in recoil terms – meaningfully more than the 270 Winchester and comparable to the 7mm Remington Magnum.
| Cartridge | Recoil (ft-lbs) | Rifle Weight (lbs) | Notes |
|---|---|---|---|
| 270 Winchester | 16-17 | 8.0 | The O’Connor standard; light and excellent |
| 270 WSM | 18-20 | 8.0 | Short-action alternative |
| 270 Weatherby Magnum | 22-25 | 8.5 | Full magnum; noticeably more than 270 Win |
| 7mm Remington Magnum | 20-23 | 9.0 | Similar class; heavier rifle helps |
| 300 Winchester Magnum | 22-25 | 9.0 | Similar energy class |
The Weatherby Mark V’s heavy receiver and quality recoil pad help manage the 270 Weatherby Magnum’s recoil. In lighter sporters or custom builds, the recoil is more apparent. Extended bench sessions for load development benefit from a quality recoil pad or rifle rest.
Ballistics and Field Performance
Trajectory
The 270 Weatherby Magnum’s velocity advantage produces a noticeably flatter trajectory than the 270 Winchester at extended range. The numbers are genuine and represent a real practical advantage for hunters who engage game at 400-500 yards.
| Distance (yards) | Velocity (FPS) | Energy (ft-lbs) | Drop (inches) |
|---|---|---|---|
| Muzzle | 3,400 | 3,338 | -1.5 |
| 50 | 3,285 | 3,115 | +0.3 |
| 100 | 3,174 | 2,905 | +1.0 |
| 150 | 3,065 | 2,711 | +0.7 |
| 200 | 2,959 | 2,527 | 0.0 |
| 300 | 2,754 | 2,191 | -5.2 |
| 400 | 2,558 | 1,889 | -15.5 |
| 500 | 2,370 | 1,620 | -32.2 |
| 600 | 2,190 | 1,384 | -56.5 |
130-grain hunting bullet, BC 0.392, 3,400 FPS muzzle velocity. 59°F, sea level, 1.5-inch sight height, 200-yard zero.
At 500 yards the 270 Weatherby delivers 1,620 ft-lbs – well above the threshold for deer and approaching adequate for elk. At 600 yards it is at 1,384 ft-lbs. Compare this to the 270 Winchester with the same bullet at approximately 1,167 ft-lbs at 500 yards. The Weatherby’s energy advantage at distance is real and meaningful for open-country hunters.
Caliber Comparison
| Cartridge | Bullet (gr) | MV (FPS) | Energy @400 yds | Drop @400 yds (200-yd zero) |
|---|---|---|---|---|
| 270 Winchester | 130 | 3,060 | ~1,399 ft-lbs | ~19.0 in |
| 270 WSM | 130 | 3,275 | ~1,700 ft-lbs | ~17.0 in |
| 270 Weatherby Magnum | 130 | 3,400 | ~1,889 ft-lbs | ~15.5 in |
| 7mm Remington Magnum | 140 | 3,150 | ~1,870 ft-lbs | ~17.0 in |
Reloading the 270 Weatherby Magnum
Primers
Large rifle magnum primers are required for the 270 Weatherby Magnum. The large case and slow-burning powders demand the consistent, energetic ignition that magnum primers provide.
| Primer | Type | Application |
|---|---|---|
| Federal 215 | Large Rifle Magnum | Hottest standard primer; excellent with slowest powders; cold conditions |
| CCI 250 | Large Rifle Magnum | Standard choice; reliable; widely available |
| Federal GM215M | Large Rifle Magnum Match | Precision loads; lowest standard deviation |
| Remington 9-1/2M | Large Rifle Magnum | Dependable; good for hunting loads |
| Winchester WLRM | Large Rifle Magnum | Consistent; works well with slow powders |
Cases
Norma and Weatherby are the primary sources of 270 Weatherby Magnum brass.
| Brand | Notes |
|---|---|
| Weatherby | Factory equivalent; available from Weatherby direct; consistent dimensions |
| Norma | Premium quality; excellent consistency; preferred by many precision handloaders |
| Nosler | Good quality when available; consistent dimensions |
The belted case requires attention during sizing. The belt controls headspacing, so shoulder bump sizing is not the primary technique here. Full-length size to ensure the case chambers reliably. Belted cases can develop a slight thickening just ahead of the belt after multiple firings – check case head wall thickness after 5-6 firings to monitor for this condition.
Trim to 2.539 inches after each firing. Anneal every 3-4 firings to maintain neck tension in the large, high-pressure case. Belted magnum cases typically deliver 5-6 reloadings at full charge weights before the belt area shows excessive work hardening.
Bullets
The 270 Weatherby Magnum uses standard .277-inch bullets, giving it the same selection as the 270 Winchester and 270 WSM. The practical hunting range is 130-150 grains.
| Bullet | Weight | Type | Application | Notes |
|---|---|---|---|---|
| Nosler Ballistic Tip | 110 gr | BT | Deer, antelope; maximum velocity | Very high velocity; adequate for deer |
| Sierra GameKing | 130 gr | SBT | Deer, antelope; flat trajectory | Classic choice; accurate; verify at close-range impact velocity |
| Nosler AccuBond | 130 gr | Bonded BT | Deer, elk; versatile | Bonded handles high-velocity close-range impact |
| Barnes TTSX | 130 gr | Copper HP | Lead-free hunting | Full weight retention; California legal |
| Hornady ELD-X | 145 gr | Polymer Tip | Deer, elk; long-range | High BC; controlled expansion across velocity range |
| Nosler AccuBond | 140 gr | Bonded BT | Deer, elk; versatile | Good BC; bonded construction; proven |
| Sierra GameKing | 140 gr | SBT | Deer, elk | Accurate; reliable |
| Berger VLD Hunting | 140 gr | VLD | Long-range hunting | High BC; precise terminal expansion |
| Nosler Partition | 150 gr | Partition | Elk, moose; tough game | Maximum penetration; controlled expansion at any velocity |
| Sierra GameKing | 150 gr | SBT | Elk, deer; big game | Most available heavy .277-inch hunting bullet |
| Hornady ELD-X | 150 gr | Polymer Tip | Elk at range; maximum energy | Highest BC in 270 WM hunting range |
At the 270 Weatherby Magnum’s muzzle velocity of 3,400 FPS, lightly constructed hunting bullets can fail catastrophically at close-range impact before achieving adequate penetration on large game. For elk and moose, use bonded or partition-style bullets that maintain structural integrity across the full velocity range. The Nosler Partition 150-grain is the safest choice for large, tough-bodied game.
Powders
The 270 Weatherby Magnum’s large case and pressure target require the slowest available rifle powders. Faster powders like Hodgdon H4350 are too fast for this case with heavy bullets – they produce partial fill and position sensitivity.
| Powder | Bullet Weight | Start Charge | Max Charge | Approx Velocity | Notes |
|---|---|---|---|---|---|
| Hodgdon H1000 | 130-140 gr | 76.0 gr | 84.0 gr | ~3,410 FPS | Top choice for 130-140 gr; consistent; excellent case fill |
| Hodgdon H1000 | 140-150 gr | 74.0 gr | 82.0 gr | ~3,220 FPS | Best with heavier hunting bullets |
| Hodgdon Retumbo | 130-150 gr | 77.0 gr | 85.0 gr | ~3,400 FPS | Very slow; excellent case fill; top velocity option |
| Hodgdon Retumbo | 150 gr | 75.0 gr | 83.0 gr | ~3,150 FPS | Best with heaviest bullets |
| Alliant Reloder 26 | 130-145 gr | 77.0 gr | 85.0 gr | ~3,380 FPS | Temperature stable; competitive velocity; good choice for hunting |
| Alliant Reloder 26 | 145-150 gr | 75.0 gr | 83.0 gr | ~3,200 FPS | Works with heavier bullets |
| Alliant Reloder 25 | 130-150 gr | 76.0 gr | 84.0 gr | ~3,350 FPS | Good all-around choice; consistent |
| IMR 7828 SSC | 130-145 gr | 74.0 gr | 82.0 gr | ~3,310 FPS | Short cut; meters well; good velocity |
| Vihtavuori N560 | 130-145 gr | 74.0 gr | 82.0 gr | ~3,300 FPS | Premium consistency; good for precision loads |
| Alliant Reloder 22 | 130-140 gr | 73.0 gr | 81.0 gr | ~3,300 FPS | Good with lighter bullets; consistent |
| Hodgdon H4831SC | 130-140 gr | 72.0 gr | 80.0 gr | ~3,280 FPS | Slightly faster; best with lighter bullets |
| Accurate MagPro | 130-145 gr | 74.0 gr | 82.0 gr | ~3,290 FPS | Ball powder; consistent metering |
| Ramshot Magnum | 130-145 gr | 74.0 gr | 82.0 gr | ~3,280 FPS | Ball powder; reliable; consistent |
All charge weights are reference figures. Verify against current Weatherby, Hodgdon, Alliant, or Nosler published data before loading. These are large charges in a high-pressure cartridge – begin 10% below maximums and work up in 0.5-grain increments. Watch carefully for pressure signs.
Hodgdon H1000 is the most practical starting point for 270 Weatherby Magnum load development. Its burn rate is well-matched to this case with 130-140 grain bullets, it fills the case consistently without position sensitivity, and it produces excellent velocity and accuracy. Most published Weatherby magnum data was developed with H1000 or Retumbo.
Hodgdon Retumbo is the slower alternative that produces maximum velocity with 130-140 grain bullets and best case fill with 150-grain bullets. Some barrels shoot Retumbo loads with slightly better consistency than H1000. Develop both and compare in your specific rifle.
Alliant Reloder 26 is the temperature-stable choice for hunters who develop loads in warm conditions and hunt in cold mountain air. Its temperature stability is the best of the common slow-burning magnum powders, and for the 270 Weatherby Magnum’s hunting application – where velocity consistency between the development bench and the hunting field matters – this stability is a meaningful practical advantage.
Practical Hunting Applications
Deer and Antelope
The 270 Weatherby Magnum with a 130-grain load at 3,400 FPS is one of the flattest-shooting deer and antelope cartridges available. At a 200-yard zero, holdover to 400 yards is approximately 15.5 inches – competitive with the flattest factory-chambered .30-caliber magnums. For antelope hunters in open terrain where 400-yard shots are realistic, the trajectory advantage over the 270 Winchester translates to a reduced holdover requirement and more margin for range estimation error.
Use a bonded bullet like the Nosler AccuBond 130-grain rather than cup-and-core bullets for deer and antelope at 270 Weatherby velocities. The 3,400 FPS impact velocity at close range can cause lightly constructed bullets to fail catastrophically before achieving adequate penetration.
Elk and Large Game
With a 150-grain Nosler Partition at 3,050-3,100 FPS, the 270 Weatherby Magnum is a capable elk cartridge to 450-500 yards, delivering approximately 1,500-1,600 ft-lbs at those distances. The 150-grain load is the appropriate choice for elk, providing the bullet weight and controlled-expansion construction that elk hunting demands. For larger animals like moose, the Nosler Partition 150-grain provides the deepest penetration available in .277-inch bore.
Mountain Hunting
The 270 Weatherby Magnum in a Weatherby Mark V or comparable long-action rifle is heavier than a purpose-built short-action mountain rifle, which is the design trade-off of a belted magnum in a full-length action. For hunters who prioritize maximum .277-inch velocity over light weight, the cartridge delivers. For hunters who want a lightweight mountain package, the 270 WSM in a short action is the more practical choice.
Conclusion
The 270 Weatherby Magnum does what Roy Weatherby designed it to do: produce the highest practical velocity from a .277-inch bore in a standard hunting rifle. At 3,400 FPS with a 130-grain bullet, it is the fastest production .277-inch cartridge available and delivers meaningful trajectory and energy retention advantages at ranges beyond 400 yards.
For hunters who understand the Weatherby freebore chamber, accept the belted case reloading considerations, and want the flattest .277-inch trajectory available, it is an excellent tool. For hunters who want a flat-shooting .277-inch cartridge in a lighter short-action rifle with more conventional reloading technique, the 270 WSM covers most of the same applications with less complexity. The 270 Winchester remains the most practical all-around .277-inch cartridge for hunters who do not need magnum velocity.
For related reading, see 270 Weatherby Magnum ballistics, 270 Winchester complete guide, and 270 WSM complete guide.
Disclaimer: All load data in this article is for reference purposes only. Verify all charges against current published reloading manuals before loading. Large rifle magnum primers are required. Never exceed published maximum charges. The Weatherby freebore chamber design requires specific attention to bullet seating depth – do not seat to contact the lands without measuring your specific chamber. Always begin 10% below listed maximums and work up while monitoring for pressure signs.
Editorial note: This article was originally published in January 2026 and revised in April 2026. The revision added a dedicated section explaining the Weatherby freebore chamber design and its implications for reloaders, belted case headspacing explanation and full-length sizing requirement, corrected the ballistics table to 200-yard zero per site standard with data from muzzle to 600 yards, a complete powder table with 13 powders and charge weight ranges, expanded bullet selection with 11 bullets including warning on cup-and-core at high impact velocity, a four-cartridge comparison table with energy and drop at 400 yards, honest recoil figures (22-25 ft-lbs, not original’s 20), and positioning against 270 Winchester and 270 WSM for different buyer priorities.
