Winchester Super Short Magnum

Winchester Super Short Magnum, or WSSM is a line of rebated rim bottlenecked centerfire short magnum cartridges introduced by the U.S. Repeating Arms Company (Winchester Inc).[1] It is a further development of the Winchester Short Magnum concept utilizing smaller bullets, but of a still higher velocity.

WSM and WSSM family of cartridges. From left to right: .223 WSSM, .243 WSSM, .25 WSSM, .270 WSM, 7 mm WSM, .300 WSM, .325 WSM.

History

Winchester and Browning partnered to create a new shorter version of the popular WSM (Winchester Short magnum) case. The new "super short" case was to be based on design principles currently proving successful in benchrest competition, such as the 6 mm PPC and 6 mm BR Remington. In 2003 the first cartridges of this design, the .223 and .243 Winchester Super Short Magnums (WSSM), were introduced. The .25 WSSM was added to the family in 2004.

None of the cartridges has managed to capture any large market share. This is likely due in part to the fact that all three cartridges have similar performance to existing popular cartridges. In addition, the .223 and .243 versions early on attained a reputation for quickly eroding the rifling in barrels.[2] Concerns about short barrel life are a common problem for high-velocity cartridges, making the WSSM rounds no different than other high-velocity cartridges. To help mitigate the problem, Browning currently uses chrome-lined barrels on all of their guns chambered for .223 WSSM.[3]

Advantages

There are basic advantages inherent to the Short Magnum concept. The idea is that the short, fat powder column gives a more uniform load density and ignition rate and therefore a more consistent burn. This in turn should translate into improved accuracy and potentially moderate recoil due to more efficient use of propellants.

Another advantage is the action size. For example, if we compare the .25 WSSM to the .25-06 Remington, we find that the .25-06 requires a .30-06 length action, commonly called a standard or long action. The .25 WSSM case which is almost a full inch shorter, can make use of an existing short action such as used by the .308 Winchester family of cartridges. Some manufacturers have even created extra short actions to accommodate newer short rounds. The intrinsic accuracy benefits of a short, stiffer action over a long action are well-established principles of rifle design. The resulting rifle is smaller, lighter, more compact, and quicker handling as well.

Disadvantages

The relatively large diameter cases result in reduced magazine capacity and reliability.

Cartridge Family

The cartridges in this family are, in order of development:

NameYearBullet diameterNotes
.223 WSSM2002.224 in. (5.69 mm)performance similar to .220 Swift
.243 WSSM2003.243 in. (6.17 mm)performance similar to 6 mm Remington
.25 WSSM2004.257 in. (6.53 mm)performance similar to .257 Roberts and .25-06 Remington

Like any new case introduced, wildcatters like to see what they can do to make new cartridges. Two of the more notable children or offshoots of this case are the .325 Corbin, which is essentially an 8 mm WSSM,[4] and the .22/40 SMc, which is essentially the .223 WSSM with an elliptical shoulder.[5]

A wildcat cartridge based on the .25 WSSM, called the .358 WSSM or .358 BFG, has similar performance to the standard .358 Winchester and .35 Whelen.[6]

See also

References
  1. De Haas, Frank; Wayne Van Zwoll (2003). "Short Stature, Long Range". Bolt Action Rifles - 4th Edition. Krause Publications. pp. 636–643. ISBN 978-0-87349-660-5.
  2. "Barrel-Burners" by Craig Boddington from Guns & Ammo, December 2004
  3. "223 WSSM vs the 22-250 Rem" from Browning
  4. 325 Corbin (8mm WSSM)
  5. Superior Ballistics
  6. BFG Design
Notes
  • WSSM Zone information about WSSM cartridges and use
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