.338-06 A-Square

History

The release of the .338 Winchester Magnum in 1958 sparked the creation of two more .338 cartridges soon after, the proprietary .340 Weatherby Magnum and the .338-06 wildcat.  The .338-06 was based on the .30-06 case necked up to take .338” bullets with no other change. This immediately made the former but similar .333 OKH (see .338 Winchester Magnum) wildcat near obsolete due to the more readily available .338 caliber projectiles. The slight step up in bore diameter was in effect, the final evolution of Elmer Keith’s favored medium bore cartridge design.
 
The .338-06 steadily grew in popularity, mostly within the US, to a point where during the 1990’s it seemed inevitable that this cartridge would become a mainstream factory chambering. Instead, Winchester and Remington ballistic engineers became focused on the development of  magnum powered cartridges based loosely on the 404 Jeffery case.  Winchester developed its line of short magnum cartridges which would hopefully eventually include a .338. However; when Winchester engineers began experimenting with a .338 short magnum, it was found that the cartridge did not produce magnum performance but duplicated the .338-06. To this end Winchester released the .325WSM. Remington opted for the high power .338 RUM. Oddly, despite the continued popularity of the .338-06, Federal introduced the .338 Federal, based on the .308Win case necked up to .338.
 
Although the .338-06 was not adopted by the big brands, this cartridge was nevertheless  standardized and was to a limited extent a factory chambering.  During the 1980’s the 338-06 was adopted by the U.S semi-custom rifle and ammunition manufacturing company A-Square. Founded by Lieutenant Colonel Arthur B Alphin in 1979, A-Square was one of the few members of the Small Arms and Ammunition Manufacturers Institute (SAAMI) donating time and money towards the rigorous testing of ammunition and chambers. This work results in the standardization of factory cartridges and rifle chambers allowing hunters to buy a rifle of for instance Winchester brand and use Remington ammunition in the rifle safely, a vital service to the industry. A-Square’s adoption of the .338-06 enabled the cartridge and chamber specifications to be SAAMI standardized. Due to this establishment, the standardized cartridge can be referred to as the .338-06 A-Square.
 
A-Square closed its doors in 2012, a thoroughly well respected company retired with dignity.
 
The .338-06 A-Square maintains a small level of popularity, enjoyed as a practical larger medium game cartridge, a working cartridge that can be relied on to get the job done. This cartridge is not to be confused with the .338 A-Square, a now rare belted magnum designed by Alphin of A-Square. This cartridge was based on the .378 Weatherby necked down to .338 caliber with a 35 degree shoulder angle rather than the traditional Weatherby radius. Performance was identical to the current .338-378 Weatherby Magnum.

 

Performance

The key consideration of the .338-06 A-Square is game body weights.
 
While I have discussed .338 projectile performance within the .338 Winchester Magnum text, the differing muzzle velocities between the .338 Win Mag and .338-06 A-Square have a major effect on results with game body weights being a major influence.
 
Although the medium bores are often expected to produce wider and fasting killing wound channels than smaller bores when used on light through to large game, .338” bullets traveling at velocities below 2600fps can be slow killers with rear lung shots, most specifically if body weight resistance is less than optimal.
 
On game weighing less than 90kg (200lb) and viewing game broadside, shots that strike in line or slightly forwards of the foreleg produce the fastest kills, often inside 2-3 yards. Shots that’s strike behind the foreleg into the heart or higher and into the rear lungs can allow animals to escape considerable distances. Bullet design and bullet weight also influence results. As an example, 180 to 200 grain fast expanding bullets can be driven fast enough to deliver hydrostatic shock on light through to mid weight game at close to moderate ranges. The frangible Rocky Mountain 225 grain ULD can anchor lean game very quickly with rear lung shots, down to very low velocities.
 
As body weights are increased, the .338-06 comes into its own. Those who live or hunt in areas where game typically weigh between 90 and 320kg (200-700lb) while occasionally taking heavier game, will find the .338-06 A-Square to be a noble cartridge. Low impact velocities will still allow rear lung shot game to run- however a good measure of target resistance ensures maximum energy transfer with a wide range of bullet designs.
 
On large animals in the 450kg (1000lb) range and heavier, the .338-06 A-Square again does not produce enough velocity to initiate hydrostatic shock. By the same token, it cannot produce wide wounding in the same manner as the magnums, especially those of a wider bore diameter. Nevertheless, with both careful bullet selection and shot placement, the .338-06 A-Square can be relied on in a utilitarian manner. Heavy bullets of suitable construction driven at low velocities can be used to break through large shoulder bones and penetrate through to and destroy vitals. That said, on densely muscled game such as bovines, a good deal of energy and wounding potential can be lost when heavy bone is encountered. Nevertheless, the .338-06 A-Square can be used in such roles. In order to produce faster kills on heavy game with both front and rear lung shots, wider bores are more effective. Long for caliber bullets of .338” diameter must be driven fast to obtain similar performance.
 
The .338-06 A-Square places less stress on projectiles than the magnums. This can be both good and bad. Generally speaking, .338 caliber bullets are made slightly tougher than their small bore counterparts. The negative result of this can be a lack of energy transfer on lean game. In contrast to this, the mild velocities of the .338-06 A-Square can allow the shooter to tackle a wide range of game body weights without being reliant on premium bullet designs with the exception of heavy game. This factor adds further weight to the .338-06 A-Square being a reliable utilitarian cartridge for those who mostly hunt large bodied medium game.

As already suggested, shot placement has a major effect on the performance of this cartridge. Those who primarily utilize meat saver shots may find the .338-06 A-Square to be far from spectacular while those who take shoulder shots will find this cartridge to be emphatic and less reliant on matching bullets to game body weights with regard to light or lean game. Obviously, precise shot placement can be a tricky affair in the field, especially at extended ranges. Here again we find varied results, the skilled shooter with an accurate rifle achieving consistently fast kills, the novice having less than ideal results.  By the same token, the woods hunter who is able to utilize high impact velocities will see very emphatic kills while those who shoot at extended ranges and pay less attention to bullet design and shot placement will see different results.
 
As for the effective range of the .338-06 A-Square, this again comes down to bullet designs and field accuracy. This cartridge is an emphatic bush / woods hunting cartridge on lean through to large bodied medium game and adequate for relatively heavy game. But as ranges are extended, component selection can become somewhat more critical. Many premium projectiles do their best work at impact velocities of 2400fps and above- basically very close woods ranges for the .338-06. A vast majority of projectiles lose the ability to create broad wounding below 2200fps or a range of around 150 to 200 yards but can produce wide wounding down to 1800fps or roughly 400 yards with carefully placed shoulder shots- again shot placement becomes a key issue. The Rocky Mountain ULD can be put to use out to ranges of 1000 yards and beyond in expert hands and is adequate for use on game up to the size of Elk. Again, effective range is relative to both bullet design and field accuracy.

 
 
 

Factory ammunition

In 2001 Weatherby adopted the .338-06 A-Square as a factory rifle chambering. Weatherby produced one factory load for their rifles featuring the 210 grain Nosler Partition at an advertised 2750fps however this ammunition has since been discontinued.
 
Nosler currently list several custom loads for .330-06 A-Square users (U.S only). This ammunition is extremely expensive and no doubt beyond the budget of many hunters. Unfortunately I have not been able to test any of this ammunition due to a lack of availability, nor have I been able to rely on the correspondence of peers. Hand loaders will note that the velocities given for Nosler ammunition are very optimistic and higher than average velocities I have listed as being obtainable with hand loads. Nosler loads include the 180 grain Accubond at an advertised 2950fps, the 200 grain Accubond at 2800fps, the 210 grain Partition at 2725fps, the 225 grain Accubond and Partition at 2575fps and the 250 grain Partition at 2475. 

 

Hand loading

 
The .338-06 A-Square is for the most part, a hand loading only proposition. In my experience, it is common to see quite high velocities quoted, but in practice, the most accurate loads along with good case life tend to be a little lower than often suggested. This is also one of the few instances where load manuals tend to be overly optimistic.

Typical velocities from a 24” barrel include 3050fps with the Barnes 160 grain TTSX, 2850fps with 180 grain bullets, 2650fps with 200 grain bullets, 2550fps with 225 grain bullets and 2450fps with 250 grain bullets. Some rifles will achieve optimum accuracy with velocities up to 100fps or more higher than these averages however if more power is wanted than the velocities given here, the hunter should consider a more powerful cartridge. 
 
The .338-06 A-Square performs well with medium burning rate powders in the IMR 4064, ADI2208/ Varget range for light bullets with H4350 (ADI 2209) being ideal for 225 grain bullets and heavier. The .338-06 would perform extremely well and produce a potential 100 to 150fps gain over standard loads with Hornady Superformance powder (high bulk density H4831sc / ADI 2231sc burn rate) however I have not yet tested this.
 
Having discussed the bulk of our .338 projectiles and their performance in the .338 Winchester magnum text which serves as our base article for the .338’s, the following text will explore select bullet designs.
 
Hornady offer a number of useful projectiles for .338-06 shooters. The SST design has dramatically altered the performance and potential of the .338 bore. This bullet design is often in high demand and shortages have occurred and to this end, we must address the more traditional Interlock designs.
 
The 200 grain Hornady Interlock and the flat point Interlock (designed for the .33 Winchester) are modest, economical lightweight .338” projectiles. These bullets are ideal for game weighing between 90 and 180kg (198-396lb) but cannot be expected to produce high shock from the moderate muzzle velocities of 2650fps typically achieved. That said, the flat point bullet can produce a higher degree of trauma at close ranges which can be very useful. But of round and flat nosed bullet designs, the most dramatic changes in performance can be seen in the .358 bores and wider. The two Interlock projectiles are suitable for lightly raking shots but not tail on shots on mid weight game. Good shot placement is the key to effect fast killing with these bullet designs. Both bullets can also be used to tackle Elk sized game due to mild impact velocities which place less stress on these projectile designs than the magnums.
 
The 200 grain SST is a useful bullet for light or lean game in the .338-06. Again, shot placement is the key to in order to effect fast kills at extended ranges. This bullet can also tackle relatively heavy animals when driven at typical .338-06 velocities and can therefore be considered a versatile performer. The SST can be used to establish baseline performance of the .338-06 on light through to mid weight game. Few other bullets can produce such wide wounding for fast as possible killing in this cartridge. Put another way, the 200 grain SST (or the 225 grain SST for generally heavy bodied deer) makes for a good starting point when exploring the potential killing performance of the .338-06. If penetration proves to be insufficient, the hunter can experiment with annealing, moving to the heavier 225 grain SST or the adoption of a stouter bullet design.
 
The 225 grain Hornady SST is suitable for a wide range of game weighing up to 320kg (700lb). For optimum penetration on large bodied game, the SST must be annealed (see bullet annealing tutorial) to decrease frontal area, prevent bullet blow up and obtain reasonably deep penetration. The annealed SST creates wider wound channels than other 210 to 225 grain .338” bullets. Nevertheless from a velocity of 2550fps, the SST produces slow kills with rear lung shots, especially on lean animals with best results again achieved through attention to shot placement. In this regard, the .338-06 user needs to be somewhat mindful as to which of the two SST bullets is selected, matching bullet weights to typically encountered game weights. If typical game weights are insufficient (e.g. 120lb Fallow / White Tail), it can pay to utilize the lighter SST and higher potential velocities to effect faster killing.
 
The affordable 225 grain Hornady Interbond offers premium performance in the .338-06. This bullet can be run in conjunction with the 225 grain SST as a dual load, the Interbond for woods work where raking shots may be encountered. This bullet also benefits from annealing, after which it can handle all bar tail on shots on Elk sized game.
 
Sierra produce two .338 bullets, the 215 grain Prohunter and 250 grain Gameking. Of the two, the Prohunter is perhaps the most useful bullet design, a cheap large deer / Elk bullet which can be driven relatively fast to promote wide wounding at close to moderate ranges but not so fast as to cause excessive bullet stress. I have yet to experiment with hollow pointing this bullet or the 200 grain Speer Hotcor and this modification could perhaps make these bullets somewhat more emphatic killers on lean game. The 250 grain Gameking can achieve relatively deep penetration when used in the .338-06 and must be considered a stout bullet design at these velocities. By the same token, this is not a mechanically controlled expanding bullet and it is unwise to use this bullet on heavy game.
 
Nosler offer a few useful projectiles for .338-06 users. It is a shame that the 180 grain Ballistic Tip is no longer with us, but its 180 grain Accubond counterpart can be put to good use in the 06. From a muzzle velocity of 2850fps, the Accubond stays above 2200fps out to 300 yards. Best performance occurs at impact velocities above 2400fps, however the low SD of this bullet helps promote bullet expansion and energy transfer down to 2200fps.  The mild muzzle velocities of the .338-06 also help prevent excessive strain to the bullet design when used on mid weight game. This bullet is well suited to game up to the size of Red and Mule deer but can handle somewhat heavier body weights. On lighter or lean animals, dead runs may be long at lower velocities regardless of adequate internal wounding- again indicating a need for careful shot placement.
 
The 200 grain Nosler Ballistic Tip is an adequate performer in the .338-06. This bullet is suitable for mid weight deer species (Red / Mule) and can be considered fast expanding at close ranges but stout at longer ranges. Large but not too large (body weights) is the key when using this bullet. Its performance does tend to be better in the magnums.
 
Although Nosler produce two .338 Accubond core bonded bullets weighing 200 and 225 grains, the traditional Partition bullet designs are hard to beat in the .338-06. Without core bonding in the front core, these bullets tends to work well at lower impact velocities,  readily dumping energy with the cut-off point being around 1800fps. That said, the .338 caliber Partition bullets need a good deal of body weight resistance at these lower velocities and rear lung shots may result in long dead runs. Regardless, these bullets fair better than other premium or core bonded bullets at low impact velocities. The Partition bullets are available in the weights 210, 225 and 250 grains. All three have been utilized to take game of considerable sizes. But as a rule, it pays to match bullet weights to game weights while taking anticipated ranges into consideration. If light deer through to Elk sized game are to be encountered, the 210 grain bullet is the go. If Moose are on the menu, the 225 or 250 grain bullets are the way to the go. If hunting heavy game, the 250 grain bullet is the best choice. If using a 250 grain bullet in any situation, ranges should be kept short as a means to maximize trauma. These are very basic rules.
 
Of the Speer range of bullets, the 200 grain Hotcor and 225 grain BTSP each have great merit. The Hotcor can make for a very inexpensive Elk bullet - able to tackle game of this size with relative ease, doing its best work at close to moderate ranges in order to keep velocities high. As mentioned, I have yet to experiment with hollow pointing this bullet as means to alter its performance on lean game or at low velocities.
 
The 225 grain Speer BTSP is a bullet worth considering. This is not a deep penetrating bullet design - but its soft jacket helps ensure wide wounding at lower impact velocities. The same dead runs can occur with rear lung shots, as is typical of this bore, especially on lean game, but the Speer BTSP does its best to maximize the wounding potential of the .338 bore. This (along with the SST bullets) is a projectile that can be used as a base line to establish wounding potential of the .338 bore on mid to large bodied deer. As for tail on shots, this is a tricky affair. From an ethical stand point, it can pay to avoid tail on shots unless it is known that a given bullet has the prowess to effect immediate collapse through nervous trauma with death occurring thereafter due to rapid blood loss. But even if we avoid tail on shots, there are times when a quartering shot can become a tail on shot due to animal movement during trigger let off. On the one hand, the Speer BTSP and SST bullets cannot cope with tail on shots on mid to larger bodied deer. On the other hand, wounding can be so severe as to anchor game immediately with death occurring thereafter due to femoral artery bleeding. Such factors need to be taken into consideration when comparing bullet designs.
 
Speer also produce their premium TBBC and Deep Curl bullet designs weighing 225 grains. In the .338-06, these bullets should be driven as fast as is safely possible while keeping hunting ranges as short as possible to maximize wounding potential. These bullets are best suited to large, heavy bodied game.
 
George Costello’s Rocky Mountain bullets have radically altered the potential of the .338-06. These bullets boast extremely high BC’s and are fully frangible down to velocities as low as 1400fps, allowing the .338-06 to be used at truly long ranges across a broad range of game body weights from the lightest of animals through to Elk sized game. These bullets require a relatively long magazine due to cartridge over all lengths; however bullet jump remains long due to the fact that the RBT bullets need to be seated deep enough in the case neck for optimum concentricity. The overall result is much the same as occurs in the .308 Winchester with the same level of free bore. Of the Rocky Mountain bullet designs, the 225 grain RBT bullet is perhaps the most useful in the .338-06 due to a balance of an initially high muzzle velocity while having enough bullet weight (and mild impact velocities) to enable the RBT to tackle relatively large bodied game at extended ranges- all the while rivaling the reach of the .300 Winchester Magnum.
 
Barnes produce a 160 grain TTSX bullet which can serve a dual role, tackling both light or lean game through to Elk sized animals. This bullet, like all of the Barnes bullet designs, does its best work at high velocity and as velocity falls between 2400 (250 yards) and 2200fps (335 yards), shots need to be placed carefully into the frontal chest of game in order to effect fast kills. Below 2200fps, killing can be slow. This bullet is at its best when maximum meat retrieval is a major consideration. At extended ranges, hunters may prefer a more violent bullet. Other Barnes designs include the 185, 210, 225 and 250 grain TSX bullets. Tipped TSX (TTSX) bullets are also available in the weights 185, 210, 225 and 250 grains. The .338-06 is best served with tipped bullets due to the slightly wider frontal area hidden behind the tip. Bullet weights are best kept to a minimum, the 225 and 250 grain bullets being reserved for the heaviest of game with ranges kept short to maximize trauma. 
 
A final word must go to Woodleigh who produce a range of .338 bullets. In the .338-06, the two Woodleigh bullets which stand out include the 225 grain protected point bullet design and the 250 grain round nose. Both are reliable on large, densely muscled game, the 250 grain bullet displaying good performance on heavy game, although killing can be quite delayed due to the limitations of this bore diameter. Woodleigh also produce a 300 grain bullet which is capable of producing outstanding penetration. Nevertheless, when used in the .338-06, the hunter must weigh up various factors. The lighter 250 grain bullet can be driven fast for wider wounding and in the .338-06, velocity is never so high as to cause a great deal of over expansion and shallow penetration on Bovine sized game. In contrast to this, the 300 grain Woodleigh bullet can produce outstanding penetration which can be useful on the heaviest of game- but with a sacrifice in trauma at low impact velocities. Hunters are therefore cautioned as to the limitations of each bullet design and the .338-06 in general.

 

Closing comments

The .338-06 A-Square is more economical to reload than the larger belted magnums and in many instances accuracy is more easily obtainable due to lower recoil. The smaller case design also increases magazine capacity. A functional cartridge, the .338-06 suits those wanting a mild recoiling cartridge specifically for hunting larger bodied animals at close to moderate ranges. That said, when loaded with Rocky Mountain ULD bullets, the .338 can be put to use as a highly effective long range cartridge.
 
On medium to large bodied medium game, select shot placement ensures fast killing while also lowering the need for precise bullet selection. Snap shot error, wind drift error or deliberate meat saver shots can lead to delayed killing and a need for greater care when selecting bullets. On heavy game, best results occur when using premium bullets loaded fast, the hunter stalking in close to keep impact velocities high. The rules for this cartridge are relatively straight forwards and once they are understood and followed, the .338-06 A-Square can prove to be an immensely effective cartridge.   
 
 

Suggested loads: .338-06 A-Square					Barrel length: 24”
No	ID		Sectional density	Ballistic coefficient	Observed  MV Fps	ME Ft-lb’s
1	HL	200gr SST	.250	.455	2650	3118
2	HL	Hornady SF 225gr SST/IB	.281	.515	2550	3248
3	HL	225gr Rocky Mountain	.281	.773	2550	3248
4	HL	250gr Woodleigh RN	.313	.332	2450	3332

 

Suggested sight settings and bullet paths
1	Yards	100	235	274	300	325	350
	Bt. path	+3	0	-3	-6	-9	-12.7
2	Yards	100	226	263	300	325	350
	Bt. path	+3	0	-3	-7	-10.3	-14.1
3	Yards	100	233	273	300	325	350
	Bt. path	+3	0	-3	-5.8	-8.8	-12.2
4	Yards	50	100	177	208	250	275
	Bt. path	+1	+2	0	-2	-6.5	-9.9

 

No	At yards	10mphXwind	Velocity	Ft-lb’s
1	300	7.1	2119	1993
2	300	6.5	2088	2178
3	300	4.2	2237	2499
4	100	1.1	2210	2711

 
 

.338-06 A-Square	Imperial	Metric
A	.473	12.01
B	.471	11.96
C	17 Deg
D	.441	11.2
E	.369	9.37
F	1.948	49.48
G	.432	8.38
H	2.494	63.34
Max Case	2.494	63.34
Trim length	2.484	63.2

 
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