.243 WSSM

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.243 WSSM
Type	Rifle
Place of origin	USA
Production history
Designer	Browning / Winchester
Designed	2003
Manufacturer	Winchester
Specifications
Parent case	.300 WSM
Bullet diameter	.243 in (6.2 mm)
Neck diameter	.291 in (7.4 mm)
Shoulder diameter	.544 in (13.8 mm)
Base diameter	.555 in (14.1 mm)
Rim diameter	.535 in (13.6 mm)
Rim thickness	.054 in (1.4 mm)
Case length	1.670 in (42.4 mm)
Overall length	2.36 in (60 mm)
Rifling twist	1-10"
Primer type	Large rifle
Ballistic performance
Bullet weight/type	Velocity	Energy
58 gr (3.8 g) VMax	4,068 ft/s (1,240 m/s)	2,132 ft·lbf (2,891 J)
70 gr (4.5 g) BT	3,707 ft/s (1,130 m/s)	2,136 ft·lbf (2,896 J)
80 gr (5.2 g) BTSP	3,545 ft/s (1,081 m/s)	2,233 ft·lbf (3,028 J)
90 gr (5.8 g) SFT	3,280 ft/s (1,000 m/s)	2,151 ft·lbf (2,916 J)
100 gr (6.5 g) BTSP	3,136 ft/s (956 m/s)	2,184 ft·lbf (2,961 J)
Test barrel length: 24" Source: Hodgdon ^[1]

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.^[2]

1 Design
2 Problems
3 Performance
4 See also
5 References
6 External links

[edit] 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.^{[citation needed]}

[edit] Problems

Short fat cases with an abruptly angled shoulder have a history of being difficult to feed properly from the magazines of some rifles.^[3] 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.

[edit] Performance

In their ballistics tables, Winchester list a very high muzzle velocity of 4,060 ft/s (1,240 m/s) with a 55-grain (3.6 g) projectile for this cartridge.^[4] Based on Hodgdon reloading data typical velocities should range from approximately 4,000 ft/s (1,200 m/s) with a 58-grain (3.8 g) bullet to approximately 3,000 ft/s (910 m/s) with a 100-grain (6.5 g) bullet.^[1] 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.