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.243 Winchester Super Short Magnum (WSSM)


The first ever short but wide cased 6mm cartridge to be developed was the 6mm Benchrest Remington released in 1962. This cartridge fires an 80 grain bullet at 2800fps and became a major success as a benchrest competition cartridge. Later, Norma increased the 6mmBR neck length and base diameter to produce the 6mm Norma Benchrest, this fires a 100 grain bullet at 2950fps and remains popular to this day for competition shooting out to 600 yards. Next came the 6mm PPC created for benchrest shooting in 1975, it has dominated 100, 200 and 300 yard benchrest for many years. The 6mm PPC fires a 100 grain bullet at around 2800fps, slightly more powerful than the 6mmBR and slightly less powerful than the 6mm Norma ( the above velocities are all from 28" target barrels ). The latest cartridge to be used in benchrest competition is the .243 Winchester Super Short Magnum which although designed primarily as a varmint to deer cartridge, has shown merit on the 600 yard range.

The .243WSSM was released, along with the .223WSSM in 2003. In 2006, production of Winchester rifles was discontinued due to financial difficulties (see .25WWSM for full history). The parent company, FN Herstal, have continued to produce .243WSSM rifles under the Browning brand however, it must be noted that while Browning rifles often produce great accuracy, the overall quality of the Browning bolt action rifle is poor. The Browning action is well designed from a manufacturing point of view but for hunters, target shooters, custom gun builders, gunsmiths and rifle lovers in general, the Browning is poorly suited to after factory tuning or modification - especially in comparison to both the push feed and control feed Winchester bolt action rifles.



For factory ammunition users, the .243WSSM gives slightly higher velocity than the .243 Winchester, producing the same velocities as factory ammunition for the 6mm Remington. With Hand loads, the .243 Winchester and .243WSSM produce almost identical velocities in barrels of equal length. This is a cartridge ideally suited to youths and factory ammunition users. A major advantage of the .243WSSM is that the original Winchester rifles designed for this cartridge were scaled down to a weight and size suitable for young hunters in the 11 to 15 year age bracket. That said, the WSSM’s were not designed primarily as “youth” cartridges therefore the rifle stocks of both the Browning and Winchester need to be shortened to suit. 

As a last reiteration, the 6mm’s excel on game weighing between 40 and 60kg (90-130lb) and at the limit of versatility on game weighing 80kg (180lb) or up to 100kg (220lb) when utilizing the Barnes projectiles in hand loads. The 6mm’s are not particularly good on Boar (Sus scrofa) due to the heavy shoulder shields of these animals which reach 1” thickness as body weights approach 80kg. On Boar, careful shot placement through “soft spots” is paramount. On heavy boned deer species weighing in excess of 100kg, it is imperative that the hunter aim to strike and destroy the shoulder bones rather than aim for soft spots.  Great success can be achieved once these contradictions are understood. 

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Factory Ammunition

Factory ammunition for the .243WSSM is still readily available and is produced by Olin who own the Winchester brand name. Olin’s varmint load features the 55 grain Ballistic Silvertip at 4060fps while the two medium game loads include the violent 95 grain Ballistic Silvertip at 3250fps and the 100 grain PowerPoint at 3110fps. The 55 grain load tends to achieve the stated velocity while the 95 grain bullet usually achieves around 3150fps. The 100 grain PowerPoint is more prone to produce 3050fps in the 24” barreled Browning and Winchester rifles.

Of the medium game loadings, the 95 grain BST is designed for open country work on thin skinned lightly built game while the PowerPoint is designed for slightly tougher game due to the controlled expanding bullet design. In truth, the PowerPoint is no stouter than the BST and at close ranges, both loads have similar limitations and are best suited to game weighing less than 80kg (180lb). The PowerPoint has a very poor BC and loses velocity very quickly. For this reason, as ranges exceed 200 yards, the PowerPoint shows slightly better controlled expansion than its BST counterpart. Nevertheless, game weight limitations remain the same and of the two loads, the BST offers a flatter trajectory and as mentioned several times throughout these texts, a violent wound channel for fast killing. 


Hand Loading

Brass for the .243WSSM can be obtained through any Winchester / Olin dealer and such dealers are found world wide. Olin is a very strong company and it is likely that 243WWSM brass will be available for many years to come. The most suitable powders for the .243 WSSM are the medium burning 4064 and Varget for light varmint bullets while medium slow burners such as H4350 and IMR4350 are the optimum choice when loading 85 to 105 grain bullets. Reloaders are urged to be careful not to either under or over load the .243WSSM, as this is a pressure sensitive cartridge.

Maximum safe working velocities for hand loads from 24” barreled rifles generally produce the same velocities as factory ammunition, typically 3300fps with 85 grain bullets, 3150fps with 95 grain bullets and 3050fps with 100 grain bullets. These velocities are within 30fps of average velocities for hand loads from 24” barreled .243Win or 22” barreled 6mm/.244 Rem rifles. For further comments on projectile performance and performance in general, the reader is referred to the .243 Winchester which serves as the base text for the 6mm’s.


Closing Comments

The .243WSSM does not break any new ground as far as exterior or terminal ballistics is concerned. This cartridge basically duplicates what other cartridges have been producing for many decades. The true virtue of the .243WWSM is the potential for scaled down rifles. Unfortunately, the WSSM’s were perhaps marketed incorrectly. The Winchester and current Browning rifles really needed a shorter than normal butt stock, adjustable to suit all members of a family of hunters. The WSSM’s could well have been the ideal youth/family rifle. Instead, the .243WSSM and its kin have rapidly faded into obscurity.
Suggested loads: .243WSSM Barrel length: 24”
No ID   Sectional Density Ballistic Coefficient Observed  MV Fps ME
1 FL 55gr BST .133 .276 4060 2012
2 FL 95gr BST .230 .400 3150 2093
3 FL 100gr PowerPoint .242 .356 3050 2065
4 HL 85gr Partition/GK/TSX .206 .315 (Av) 3300 2055
Suggested sight settings and bullet paths         
1 Yards 100 150 275 319 350    
  Bt. path +1.5 +2 0 -2 -4    
2 Yards 100 175 285 330 350 375 400
  Bt. path +3 +3.7 0 -3 -5.2 -7.9 -11
3 Yards 100 150 270 310 350 375 400
  Bt. path +3 +3.7 0 -3 -7.2 10.3 13.9
4 Yards 100 150 292 330 350 375 400
  Bt. path +3 +3.9 0 -3 -4.7 -7.4 -10.4
No At yards 10mphXwind Velocity Ft-lb’s
1 300 7 2935 1052
2 300 6.3 2489 1306
3 300 7.5 2329 1204
4 300 7.8 2450 1133

243  wssm final.jpg
  Imperial Metric 
A .535 13.6
B .555 14.09
C 28deg  
D .544 13.81
E .291 7.39
F 1.150 29.21
G .282 7.16
H 1.670 42.41
Max Case 1.670 42.41
Trim length 1.660 42.16

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