.243 WSSM

The .243 Winchester Super Short Magnum or .243 WSSM is a fairly new rifle cartridge, introduced in 2003. It uses a shortened .300 WSM (Winchester Short Magnum) case shortened and necked down to accept a .243in/6mm diameter bullet, and is a high velocity round based on ballistics design philosophies that are intended to produce a high level of efficiency.

Design
The .243 WSSM is an addition to the Winchester Super Short Magnum (WSSM) family of cartridges, which also include the .223 WSSM and the .25 WSSM, and the idea behind the .243 WSSM was to develop a compact, higher velocity version of the well-established and internationally popular .243 Winchester unveiled by Winchester in 1955.

The .243 WSSM's case is unusually short and fat in profile, contrasting markedly with most other rifle cartridges, and is intended to take advantage of what ballisticians have shown is the more uniform and efficient burning of propellant powder when it is held in a short, fat stack by the cartridge case.

Problems
Short fat cases with an abruptly angled shoulder have a history of being difficult to feed properly from the magazines of some rifles. In addition, during its short life the WSSM family of cartridges has already gained a reputation for being hard on gun barrels because of the high velocities involved, although this is a point of some dispute among various knowledgeable gun owners and expert writers.

Some rifle manufacturers such Browning have also taken to chrome-lining their barrels' bores to make them less susceptible to the wear caused by the high levels of bullet friction and very high propellant gas temperatures that occur with WSSM cartridges.

Performance
In their ballistics tables, Winchester Repeating Arms Company list a very high muzzle velocity of 4060 ft/sec with a 55 grain projectile for this cartridge. Based on Hodgdon reloading data typical velocities should range from approximately 4,000 ft/sec with a 58 grain bullet to approximately 3,000 ft/sec with a 100 grain bullet. The percentage gain in performance over the older .243 Winchester is around 10% or less, and it remains to be seen if the market will offer a commercially viable place to two 6 mm sporting cartridges that have such similar performance.

This cartridge is usually used for small game such as varminting, and used for animals as big as deer.

Categories
Cartridge:rifles