.270 Winchester Short Magnum

History

Following the immediate success of the .300 WSM in 2001, the .270 and 7mm WSM were introduced in 2002. The last of these cartridges, the .325 WSM, was introduced in 2005.
 
Like its siblings, the .270 WSM has gained a steady following for a variety of reasons. One of the foremost factors in the success of these cartridges has been the reduction in both size and weight of rifles in comparison to traditional magnum chamberings. The .270 WSM has also given fans of the .270 Winchester a cartridge which boasts greatly enhanced performance supported by readily available factory ammunition.  
 
These cartridges have quickly became popular world wide, with a variety of ammunition found in gun stores around the world. The WSM’s have also received a small amount of negative criticism. Poor magazine to chamber feeding and excessive pressures resulting in difficult extraction have been major complaints. Both of these issues have been addressed at a design level. The most recent of complaints has been the cost of ammunition, ever rising due to metal market demands in developing nations. 
 
The .270 WSM is the third in what is now called the trio of .270 (.277”) caliber commercial cartridges. These include the .270 Winchester, .270 WSM and the .270 Weatherby Magnum.
 

Performance

The .270 WSM sits roughly halfway between the .270 Winchester and .270 Weatherby Magnum in power.  Hand loads and more especially the Hornady Light Magnum loads for the .270 Winchester can come close to .270 WSM velocities however, the WSM is able to achieve its goal velocities with relative ease.
Firing 130 grain bullets at between 3250fps and 3300fps, the .270 WSM is capable of delivering high shock for impressively fast killing out to ranges of around 300 yards along with clean but sometimes slightly delayed killing out to 400 yards. After approximately 500 yards, wound channels become proportionate to the expanded bullet.

With heavier 150 grain bullets driven at 3150fps, the increase in BC produces the same killing performance over varying ranges as the lighter 130 grain bullet weight. The .277 caliber absolutely shines when loaded with 150 grain bullets to 3000fps and faster, producing fast kills and deep penetration on a huge variety of game. By the same token, the .270 WSM is not so powerful as to push 150 grain bullets up into the 3200-3300fps ultra velocity range. Ultra velocity can, if the projectile is not designed to operate as such, cause excessive stress to projectiles at close to moderate range impact velocities with a seemingly unusual drop in killing performance. The WSM avoids this problem to a larger degree.
 

Factory Ammunition

Since the introduction of the .270 WSM, Olin has continued to broaden it’s range of factory ammunition. Current loads include the 130 grain Ballistic Silvertip at 3275fps, the 130 grain Power Max at 3275fps, the 130 grain XP3 also at 3275ps, the 140 grain Accubond at 3200fps, the 150 grain PowerPoint at 3150fps, the 150 grain Ballistic Silvertip at 3120 and finally, the 150 grain XP3 at 3120fps.
 
The 130 grain BST is a very fast expanding, violent killing projectile. Like so many small bore projectiles, the BST produces its fastest kills at impact velocities of above 2600fps (325 yards), producing wide wounding but sometimes slightly delayed killing between 2600 and 2400fps. Rear lung shots beyond this range, out to 525 yards, tend to be delayed but clean. The 130 grain bullet can produce spectacular exit wounds when used on light weight game weighing 60kg (130lb) and less and is best suited to game weighing no more than 80kg (180lb).
 
The 150 grain Power Max is similar in design to the Nosler Accubond if the tip were excluded in the design. The Power Max is an attempt at offering premium performance at a reasonable price. As can be expected, performance is very similar to the Accubond, albeit with much lower BC’s. Olin market this projectile solely for use on Whitetail deer and under typical moderate range / 40 acre block hunting conditions, this projectile is ideal.
 
The 140 grain Accubond really is a spectacular killer when driven at high velocity and makes for an extremely good all round lighter medium game load. In some instances entry wounds at close range can be very large, as wide as 3” with exit wounds on medium game being between .75 to 1” in diameter. The wide entry wounding occurs not due to total bullet blow up but due to a combination of factors. The Accubond is slightly different to other core bonded bullet designs in that is does tend to shed its front most core (Ogive area). One could argue the point that the bonding of the Accubond is not sound however, the reduction in frontal area also aids penetration. 
 
In the .270 WSM (and Weatherby) wide entry wounds created by the Accubond at close range are caused by immediate energy transfer which produces hydraulic shock. If the Accubond were softer, it would meet such resistance that the mass of the animal would overcome the bullet energy / wide entry wound phenomena. If the Accubond were tougher it would meet far less resistance and again, produce a small entry wound. The performance of this projectile is unique to its caliber, bullet weight, velocity and light to medium game weights. Wounding through vitals is thorough, gradually tapering off through offside muscle and bone. As can be expected, the 140 grain Accubond at magnum velocities is not the best choice for large game such as Moose.
 
The 150 grain PowerPoint is a basic, economical, entry level bullet. On the one hand, its aged design is totally lacking in ballistic efficiency, quickly losing velocity and suffering the effects of wind more so than modern designs. Yet despite its weaknesses the 150 grain PowerPoint is a devastating killer of medium game, boring deep, broad wounds, as wide as 3” in diameter through vitals and offside tissue. On impact the PowerPoint suffers gradual disintegration and cannot be expected to penetrate vitals of medium game with tail on shots however; wounding from such shots is fierce enough to incapacitate game immediately. With a BC of just .344, the violent performance of the PowerPoint diminishes at around 200 yards, beyond which, wounding is clean out to nearly 400 yards, a good practical maximum range for this bullet design.
 
The 150 grain BST driven at magnum velocity is yet another unique combination (also occurs with the 150 grain 7mm Ballistic Tip). Performance tends to be more uniform than the dramatic Accubond and PowerPoint bullets as loaded by Olin. Instead, the 150 grain BST tends to bore a narrower yet more constant wound channel. It is not uncommon to find lung fragments on the offside of downed game, well beyond the point of the kill. This projectile is a very emphatic killer, in a repeatable manner and out to impact velocities of around 2400fps or 400 yards with a gradual shift in performance at the 2200fps mark or 525 yards. Like the PowerPoint, the BST is best suited to lighter medium game, reaching its limit on game weighing 80kg (180lb).
 
The XP3 loads now replace the once innovative Fail Safe bullet designs. The new bullets are in some ways similar to the former, a copper alloy font portion, the base of the bullet filled with lead to add weight and reduce unnecessary mass. The difference with the new bullet is an increase in frontal area which is streamlined with the addition of a polymer tip. The old design was in some ways a dog. On large but lean animals, the bullet would sometimes pass through, creating very little damage. It could even be said that in some instances, the (140 grain) Fail Safe killed better with tail on shots than cross body shots. The Fail Safe certainly had no problem penetrating with tail on shots, often producing an exit wound on lighter animals.
 
The new XP3 loads overcome narrow wounding problems with ease. That said, like the Barnes TSX, these bullets do their best work at impact velocities above 2600fps with a noticeable drop in performance below this. The 130 grain XP3, thanks to an excellent BC, stays above 2600fps out to  around 325 yards, the 150 grain XP3 does so out to around 275 yards. These bullets are far superior to other Olin .270 WSM offerings when used on larger, heavy boned game such as Elk.
 
Federal loads for the .270 WSM include the 130 grain American Eagle (formally Hi-Shok) bullet at 3250fps, the 130 grain Ballistic Tip at 3300fps, the 130 grain TSX at 3280fps, the 130 grain Partition at 3280fps, the 140 grain Accubond at 3200fps, the 140 grain Trophy Bonded Bear Claw at 3200fps, the 150 grain partition at 3160fp and finally, the 150 grain Fusion load at 3080fps.
 
Federal’s 130 grain Soft Point is deigned to be as economical as possible for the end user. Performance of this projectile is greatly boosted by the WSM velocities. In the standard .270 Winchester this bullet is accurate but somewhat lack luster. In the WSM, wounding is wide and fast killing can be expected out to ranges of around 330 yards. This projectile is not ideally suited to larger, heavy boned game at close ranges. The 130 grain Ballistic Tip has already been described in its Olin BST guize, a violent killing, lighter medium bullet. The 130 grain Partition is also better suited to lighter medium game when used at Magnum velocities in order to minimize rear core separation. 80kg (180lb) is a good practical maximum for this bullet in order to maintain its excellent wounding and penetration characteristics. 
 
The 130 grain TSX is absolutely ideal for game weighing between 90kg and 320kg (200-700lb). The 140 grain TBBC produces similar performance to the TSX but it seems to be the Federal way, offering every bullet design possible in an attempt to please every hunter.
 
The 150 grain Partition driven at 3160fps is simply dynamite. Best performance is derived when this bullet is used on all game up to a weight of 150kg or 330lb and is adequate for game weighing up to 320kg (700lb). 
 
The 150 grain Fusion bullet is a great addition to the WSM loadings. The Fusion looks much like a traditional Hi-Shok or Core-Lokt bullet but is of course, core bonded. Like the Accubond, the Fusion bullet tends to lose some of its frontal area and weight during penetration. That said, energy transfer is not quite so immediate and because of this, at extended ranges, the Fusion bullet tends to produce delayed kills. Regardless, when used within 275 yards, the Fusion bullet produces fast kills on light or lean medium game. On tougher animals such as Boar, the Fusion bullet comes into its own. This projectile is not quite as thorough or emphatic as the Barnes TSX when used on Elk sized game but is nonetheless adequate.
 

Hand Loading

Optimum powders for the .270 WSM are the slow burners such as H4831sc (ADI 2213sc) through to H1000 (ADI2217) range. In truth, the optimum burning rate is right between H4831sc and H1000 and is produced by Olin in the form of Winchester WXR which is a slow burner but with a high bulk density. 

From the factory standard 24" barrel length, realistic maximum velocities for the .270 WSM tend to duplicate factory loads at 3300fps with 130 grain bullets, 3200fps with 140 grain bullets and 3100fps with 150 grain bullets. These velocities are on average, 150fps higher than maximum working loads for the .270 Winchester. One factor that has become evident is that many reloaders are complaining of difficulties obtaining full velocities and in some instances, are unable to gain anything over the original .270 Winchester cartridge. 

It must be noted that experimentation is the key. Unusually long throated rifles may need to be loaded past maximum listed loads by several grains however; this requires an understanding of how to read both throat lengths and pressure signs. In other instances, as mentioned, problems can occur relative to burning rates which can be overcome with either the use of WXR powder or further experimentation with burn rates.

The vast range of .277 caliber projectiles have been described in great detail within the .270 Winchester text. Rather than duplicate previous comments, the ahead text will attempt to address basic approaches or formulas for choosing projectiles for the WSM.

Of the 130 grain bullet options, the core bonded polymer tip designs really have an edge over conventional soft point projectiles for all around usage. Magnum velocities put terrible strain on lighter weight, low SD conventional projectiles and while results can sometimes be spectacular, disappointing results can occur when least expected.

The InterBond, Accubond and Scirocco all produce similar results, extremely violent at close range yet still producing deep wounding on medium game. These projectiles produce consistently fast kills out to 325 yards or 2600fps, slightly delayed killing out to 450 yards or 2400fps (with rear lung shots) and often slow killing beyond this range. At 600 yards where velocity is down to 2100fps, the three projectiles tend to open up to produce a frontal area of approximately .350” (9mm) with wound channels slightly larger. The 130 grain can be prone to the same close range, wide entry wound phenomenon as its 140 grain counterpart depending on game weights.

The InterBond does not produce the same wide entry wounds as sometimes occurs with the Accubond at close range. On heavy muscled game weighing between 100 and 200kg (220-440lb) or so, the InterBond produces traumatic wounding to a deeper level than the Accubond though the mechanics are subtle. The Scirocco does produce the same massive entry wounding as the Accubond if angled into the hams of medium game at close range. The Accubond tends to be the widest wounding of the core bonded designs at low velocity which is immensely useful.

The 140 grain bonded Scirocco and Accubond projectiles are much the same as the 130 grain bonded bullets without any variation in cut off points in terminal performance at varying ranges. Any loss in velocity in comparison to 130 grain counterparts is quickly made up for by an increase in BC. These are very good all round projectiles for use on medium game.

The 150 grain bullet weights offer a little more compromise with regard to consistent performance over varying ranges. The two most useful designs are (no surprise) the 150 grain Hornady SST (annealed) and Partition projectiles. Both are soft but not so soft as to suffer the disintegration that occurs with so many other soft projectiles. These projectiles come into their own at 300 yards where a stouter bullet can fail to impart its energy in an immediate manner. Furthermore, both are capable of producing end to end penetration on lighter to medium weight game.

For large tough game such as Elk, it is par for the course to mention the Barnes TSX 130 and 150 grain projectiles. Few other projectiles can compare. Nevertheless, three other excellent projectiles include the 150 grain Swift A-frame, the 150 grain Woodleigh Weldcore and 160 grain Nosler Partition semi point.  The A-Frame does not penetrate quite as deeply as the TSX due to its tendency to ball up, ending up looking much like a musket ball but this projectile is extremely reliable, doing its best work at high velocities (above 2400fps). BC of the A-Frame is .444.

The 150  Woodleigh projectile deserves a special mention. This bullet is very stout, too stout for fast killing of lighter medium game and in this regard, far different from the Accubond/ Scirocco etc.  The Woodleigh has a tip much like the A-Frame/Fusion/Hi-Shok/Core-Lokt but has a sleek ogive resulting in a reasonably high BC of .463. On heavily muscled game, the .270 Weldcore is a sledge hammer. Energy transfer is as sure as the setting sun and is deep, broad and emphatic.  For those who do not favor the entirely stout nature of the Barnes but find other bullets too unsound, the Woodleigh 150 grain bullet fills a niche for large medium game. Penetration is slightly shallower than the Barnes but weight retention is exceptionally high.

The 160 grain Nosler Partition is an excellent bullet. Although it is a semi point design and its BC of .434 may not seem that high, this bullet can be launched at velocities of 3000fps (in some cases higher), produces emphatic results out to 400 yards and is adequate to ranges of around 600 yards. This bullet is flexible regarding game body weights and although it was designed with Elk in mind, is equally effective on light bodied game. The semi point design ensures immediate and full energy transfer. The 160 grain Partition is certainly an oddity. At a glance it can appear somewhat outdated and a handicap to the fast WSM, yet in the field (in reality), this is an excellent bullet and in some ways the best of all worlds.

For long range hunting, the 150 grain Berger VLD loaded to 3100fps produces violent wounding out to 550 yards or 2200fps. Between 2200 and 2000fps, bullet expansion is sometimes dependent on target resistance and bone encountered along with annealing (see annealing tutorial). Under ideal conditions, the VLD is effective to 1800fps, maximum body weights around 150kg (330lb).
 

Closing Comments

Hunters have been thoroughly divided over the .270 WSM. Some love it, others cannot stand the idea of a cartridge that only produces 150fps more velocity than the standard .270 Winchester, as opposed to the Weatherby.
 
The greatest virtue of the .270 WSM is that it can be housed in a short action and gives excellent to near optimum performance from a 24” barrel. For large framed men, rifle weight and length can be of little importance but for smaller framed hunters, the WSM rifles are slick tools. Rifle weight distribution is yet another factor. It is a most unusual and unexplainable feeling to compare a rifle with a light weight stock combined with a stout medium length barrel as opposed to a longer barreled rifle with its weight evenly distributed. Recoil with the former seems to be more manageable.

Yet another great virtue of the .270 WSM is that it produces high velocity for excellent killing but velocity with 140 to 150 grain bullets is not so high as to create a great deal of other associated problems. The only negative of the .270 WSM is that bullet choice is (mostly) confined to 130 to 150 grain weights. The 7mm and .30 calibers have a far greater selection of bullet weights, offering greater flexibility for large medium game and long range hunting. The .270 WSM is undoubtedly suitable for 90% of the worlds game species but should never be expected to produce excellent performance beyond its design limitations.
 

Suggested loads: .270 WSM					Barrel length: 24”
No	ID		Sectional Density	Ballistic Coefficient	Observed  MV Fps	ME Ft-lb’s
1	FL	Federal 130gr soft point	.242	.367	3250	3048
2	FL	Winchester130gr BST	.242	432	3275	3096
3	FL	Winchester140gr AB	.261	.496	3200	3183
4	FL	Winchester150gr PP	.279	.344	3150	3304
5	HL	130gr InterBond	.242	.460	3300	3143
6	HL	150gr Woodleigh PP	.279	.463	3100	3200
7	HL	150gr Berger VLD	.279	.531	3100	3200

 

Suggested sight settings and bullet paths
1	Yards	100	175	297	337	375	400	425	450
	Bt. path	+3	+3.9	0	-3	-6.7	-9.6	-12.9	-16.7
2	Yards	100	175	307	345	375	400	425	450
	Bt. path	+3	+4	0	-3	-5.4	-8	-11	-14.3
3	Yards	100	175	301	340	375	400	425	450
	Bt. path	+3	+3.9	0	-3	-6	-8.7	-11.7	-15.1
4	Yards	100	150	282	320	375	400	425
	Bt. path	-3	+3.8	0	-3	-8.7	-12	-15.8
5	Yards	100	175	313	355	375	400	425	450
	Bt. path	+3	+4	0	-3	-4.75	-7.2	-10	-13.2
6	Yards	100	150	288	335	375	400	425	450
	Bt. path	+3	+3.8	0	-3	-7.5	-10.5	-13.8	-17.6
7	Yards	100	150	292	333	375	400	425	450
	Bt. path	+3	+3.8	0	-3	-6.9	-9.7	-12.9	-16.4

 

No	At yards	10mphXwind	Velocity	Ft-lb’s
1	350	9.3	2408	1673
2	425	11.6	2404	1668
3	425	10.8	2409	1804
4	300	7.5	2390	1902
5	450	12	2429	1703
6	375	8.8	2400	1919
7	550	17.1	2220	1641
12

Note: Load No.6 data can be used for the 150 grain Nosler Partition which has an identical BC. Load No.7 data can be used to plot trajectory for 150 grain SST (BC .525).
 
 

 

	Imperial	Metric
A	.535	13.58
B	.555	14.09
C	35deg
D	.538	13.66
E	.314	7.97
F	1.664	42.26
G	.277	7.03
H	2.100	53.5
Max Case	2.100	53.5
Trim length	2.090	53.08

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