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.270 Weatherby Magnum

History


The .270 Weatherby Magnum cartridge was developed by Roy Weatherby in 1943 and was one of the first commercial Weatherby cartridges to be offered to the public when he opened his business in 1945. The .270 is one of a family of Weatherby Magnums which share a 2.545” (64.64mm) length case. These include the .257, .270 and 7mm Weatherby Magnum cartridges. The .300 Weatherby Magnum has a longer case length of 2.825" (71.76mm). 

As with most of the Weatherby line of cartridges, the .270 gained a small but staunch following which has remained static to this day, regardless of new inventions such as the .270WSM. The .270 WBY is a favorite cartridge of Australian gun writer Nick Harvey for use on all game up to the size of Elk. Harvey has harvested a great number of game, including African plains game, using the 130 grain Barnes TSX.
 

Performance


As can be expected, the .270 WBY is a powerful, flat shooting, hard hitting cartridge. The Weatherby is not a specialized cartridge, regardless of its unique case design but rather, an excellent all-round medium game cartridge blessed with mild recoil (for a magnum).

Loaded with 130 to 150 grain bullets, the .270 WBY produces high shock for fast killing out to ranges of around 325 yards. Broad wounding continues out to around 450 yards after which, wound channels are more proportionate to caliber. Unfortunately, no manufacturer currently produces a wide wounding match style projectile in .277” caliber specifically for long range hunting at ranges beyond 500 yards. 

The .270 Weatherby is absolutely ideal for light to medium weight game. On larger animals such as Elk, bullet choice has a huge effect on results. Using a bullet of sound construction, the Weatherby is able to render wide, fast bleeding wounds and free bleeding exit wounds on game weighing as much as 320kg (700lb). The .270 WBY is adequate for heavier species of game but certainly not as emphatic as something in the class of the .340 WBY.
 

Factory Ammunition


Weatherby list one varmint load featuring the 100 grain Hornady soft point at a throat melting velocity of 3760fps. Other Weatherby factory loads include the 130 grain Hornady Interlock at 3375fps, the 130 grain Nosler Partition also at 3375fps, the 130 grain TSX at 3400fps, the 140 grain Nosler Ballistic Tip at 3300fps, the 140 grain Accubond at 3320fps, the 150 grain Hornady Interlock at 3245fps and finally, the 150 grain Partition, also at 3245fps. All of these loads are chronographed in 26” barrels. Velocities in sporting rifles tend to range from 100fps below advertised to within 20fps.

At 3275 to 3375fps, the 130 grain Interlock is not a particularly good performer on medium game at close ranges due to bullet blow up. Nor does the Interlock produce a necessarily wide wound channel during bullet blow up due to its tendency to disintegrate into dust, rather than larger fragments. This load is best utilized on game weighing no more than 60kg (130lb). The 130 grain Partition is a slightly better all-rounder but is still put under a great deal of stress at close range, best suited to game no heavier than 80kg (180lb) for optimum performance. 

The 130 grain TSX loaded to Weatherby velocities produces outstanding results. The combination of a high muzzle velocity plus a good BC, enables the TSX to produce high shock out to 400 yards (2600fps). There is a definite cut off point in performance when the TSX falls below 2600fps and rear lung shots often result in very slow kills, especially on light or lean animals. Nevertheless, this Weatherby load extends the ‘versatile’ or ‘shot placement forgiving’ range of the TSX out to a distance that is as far as many hunters are willing to shoot. This a good load for all game up to the size of, and especially suitable for, Elk.

Weatherby’s two 140 grain loads are also very useful. The Accubond and BT both have a similar form and will almost always shoot to the same POI. The 140 grain Accubond opens quickly on light game, causes immediate collapse with ordinary shoulder shots and renders a large wound channel. On heavy animals such as Boar or Elk, the Accubond will not exit from cross body shoulder shots, wounding is broad but the Accubond cannot be expected to produce optimum performance with heavily raking shots. The BT almost always suffers bullet blow up at close ranges. This projectile is stouter than the 130 grain Hornady but at close ranges, is still best limited to use on lighter animals. As Ranges exceed 200 yards, the BT performs well on a variety of game up to 80kg (180lb) and continues to produce wide wounding out to around 500 yards.

The 150 grain Hornady Interlock really is a spectacular game bullet however it is not in anyway a stout, deep penetrating projectile. Like the Ballistic Tip, this projectile is best suited to game weighing up to 80kg as a safe maximum. On heavy bone the Interlock is prone to total disintegration. The Interlock is definitely a more spectacular, emphatic killer on light framed animals than the BT or similar conventional style projectiles.

Federal list three loads for the .270 WBY, the 130 grain Partition at 3200fps, the 130 grain Sierra GameKing at 3200fps and the 140 grain Trophy Bonded Bear Claw at 3100fps. These are fairly mild loads but are nevertheless useful. Both the Sierra and Nosler bullets will in most cases shoot to the same POI out to ranges exceeding 300 yards. The BC of both bullets is similar, regardless of the flat base of the Partition versus the boat tail GameKing design. Both Vertical and Horizontal dispersion between loads is either non existent or minute. The 130 grain Sierra is a hand grenade on light game at close to moderate ranges, disintegrating into fragments of copper and lead. The Partition is also a violent killer but does so without bullet blow up and produces noticeably deeper penetration. To this end, Federal sell the GameKing load at a cheaper price. Both the Partition and GameKing readily expand at low velocities of 2200fps.

The Trophy Bonded Bear Claw is similar to the Barnes TSX in design but different in performance. The TBBC has a wider meplat and soft lead frontal core. The BC of the TBBC is fairly low, a reflection of the singular goal towards optimum terminal performance within “traditional” moderate hunting ranges. The TBBC opens extremely quickly, renders a violent wound channel but also produces deep penetration. The higher the impact velocity or the heavier the bone, the more violent the wound. Like the TSX, this projectile does its best work at impact velocities above 2600fps which in this loading, equates to a range of 200 yards. Beyond this range kills are clean but slightly delayed, becoming much slower at 280 yards or 2400fps.
 

Hand Loading


There is little difference in powder capacity between the .270 WBY, the 7mm WBY and the 7mm Remington magnum. The latter has a slightly shallower shoulder angle and is shorter in the neck by a meager 60 thou (1.25mm). Nevertheless, Weatherby chambers feature generous freebore which allows for long peak chamber pressures, resulting in higher obtainable velocities.

From the factory ammunition COAL of 3.280” (83.3mm), bullet jump to the lands is approximately .375" (9.525mm). The hand loader can theoretically seat bullets closer to the lands but it is impossible to seat bullets within 40 thou (1mm) of the lands due to loss of concentricity. Regardless of freebore, properly tuned Weatherby rifles will normally shoot a variety of projectiles with acceptable to excellent accuracy.

The most suitable powders for the .270 WBY are the slow burners, especially H1000 (ADI2217), IMR7828 and N170. From 26” barrels, maximum safe working velocities include 3400fps with 130 grain bullets, 3300fps with 140 grain bullets and 3200fps with 150 grain bullets.

A few years ago there were very few projectiles capable of producing optimum performance in the .270 WBY, now there are several outstanding bullet designs. As with many high power cartridges of this type, a good rule of thumb for choosing bullets is to adopt either “light but stout” or “heavy but soft” projectiles. Of the two styles, generally speaking, the heavy but soft bullets tend to be the most versatile loads on medium game due to more uniform performance at longer ranges.

Examples of the light but stout bullets include the 130 grain InterBond, 130 grain Scirocco, the 130 grain Accubond and 130 grain Barnes TSX. Of these, the core bonded bullets are a little more emphatic on lean game at longer ranges of between 300 and 400 yards while the TSX is much more thorough on larger animals. The mid weight 140 grain Accubond is a good projectile, as already mentioned.

Examples of heavy but soft projectiles which produce reliable performance include the 150 grain Hornady SST, the 150 grain Nosler Partition and the 160 grain semi point Partition. Each have their strengths and all are outstanding medium game projectiles. The SST, once annealed (see 7mm Rem Mag), is a versatile all-rounder, working very well at both close and extended ranges on mid weight deer species. This is a violent and hard hitting bullet that is worlds apart from its 130 grain counterpart. The 150 grain Partition is extremely useful on game weighing up to 150kg (330lb) while being perfectly adequate for Elk sized game. The 160 grain Partition is extremely underutilized, being ideal for a wide range of body weights and coming into its own on to Elk sized animals. Both produce emphatic results down to impact velocities of 2200fps and are adequate to impact velocities of 1800fps. Performance of the Partitions and 150 grain SST cannot be under stated. Three extremely useful projectiles.
 

Closing Comments


The .270 Weatherby continues to maintain a steady following, regardless of new inventions such as the WSM’s. The Weatherby is an emphatic killer of light to larger medium game and does so without producing horrendous recoil - two factors which will ensure it remains popular for many years to come.
 
Suggested loads: .270 Weatherby Magnum Barrel length: 26”
No ID   Sectional Density Ballistic Coefficient Observed  MV Fps ME
Ft-lb’s
1 FL WBY 130 TSXBT .244 .466 3400 3336
2 FL WBY 140gr Bal Tip .261 .456 3300 3385
3 FL WBY140gr Accubond .261 .496 3320 3425
4 FL WBY150gr Partition .279 .465 3245 3507
5 HL 130gr Hornady InterBond .244 .460 3400 3336
6 HL 150gr Berger VLD .279 .532 3200 3410
 
Suggested sight settings and bullet paths           
1 Yards 100 175 327 370 400 425 450 475
  Bt. path +3 +4.2 0 -3 -5.7 -8.3 -11.2 -14.4
2 Yards 100 175 312 355 375 400 425 450
  Bt. path +3 +4 0 -3 -4.8 -7.3 -10.2 -13.4
3 Yards 100 175 318 360 375 400 425 450
  Bt. path +3 +4 0 -3 -4.2 -6.6 -9.3 -12.3
4 Yards 100 175 306 345 375 400 425 450
  Bt. path +3 +4 0 -3 -5.4 -8 -11 -14.3
5 Yards 100 175 327 370 400 425 450 475
  Bt. path +3 +4.2 0 -3 -5.7 -8.3 -11.2 -14.5
6 Yards 100 175 306 345 375 400 425 450
  Bt. path +3 +4 0 -3 -5.4 -7.9 -10.8 -14.1
 
 
No At yards 10mphXwind Velocity Ft-lb’s
1 450 11.4 2520 1834
2 450 12.2 2422 1823
3 450 11 2503 1947
4 450 12.2 2392 1906
5 450 11.6 2510 1819
6 625 21.6 2192 1601

Note: Load No.6 shows retained velocity at 625 yards as an insight to velocities.
 
 270 weatherby magnum final.jpg

 
  Imperial Metric 
A .531 13.50
B .512 13.00
C R.151  
D .492 12.50
E .303 7.70
F 2.068 52.55
G .397 10.08
H 2.549 64.74
Max Case 2.549 64.74
Trim length 2.539 64.49

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