What Is .223 Winchester Super Short Magnum

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Last updated: April 10, 2026

Quick Answer: The .223 Winchester Super Short Magnum (WSSM) is a rifle cartridge introduced in 2003 that achieves muzzle velocities up to 4,600 feet per second, making it the fastest .22 caliber round in production. It uses a shortened magnum case design 60% heavier than comparable rounds, providing superior ballistic performance at the cost of reduced barrel life.

Key Facts

Introduced in 2003 by Winchester Ammunition and Browning Arms Company
Achieves muzzle velocities up to 4,600 feet per second with 55-grain bullets
Delivers 600 ft/s velocity gain over standard .223 Remington ammunition
Case features heavy walls and thick web, weighing 60% more than .22-250 Remington
Known for rapid barrel erosion due to high-velocity ballistics

Overview

The .223 Winchester Super Short Magnum (WSSM), also designated as 5.56×42mm, is a rifle cartridge developed collaboratively by Winchester Ammunition, Browning Arms Company, and Winchester Repeating Arms Company. It was officially introduced to the commercial market in 2003 as part of Winchester's Super Short Magnum family of cartridges.

The .223 WSSM represents an evolutionary step in magnum cartridge design, combining the proven .223 caliber with a shortened, high-capacity magnum case design. This cartridge was specifically engineered to deliver exceptional velocity and flat trajectory characteristics for hunters and shooters seeking extreme performance from a lightweight, handy rifle platform.

How It Works

The .223 WSSM operates on principles of high-pressure, high-velocity ammunition design:

Case Design: The cartridge uses a proprietary shortened magnum case with significantly thicker walls, webbing, and neck construction compared to conventional cartridges, allowing it to safely contain higher pressures.
Velocity Performance: With 55-grain bullets, the .223 WSSM achieves muzzle velocities up to 4,600 feet per second (1,402 meters per second), providing a 600 ft/s advantage over the standard .223 Remington cartridge.
Caliber Specifications: The cartridge maintains the traditional .223 caliber (5.56mm) bullet diameter while utilizing a case 60 percent heavier than the .22-250 Remington, enabling superior power delivery in a compact package.
Pressure Management: The robust case construction and thick neck rim diameter of .022 inch (compared to .015 inch for the .22-250) ensures reliable function and safety at sustained high pressures.

Key Comparisons

Cartridge	Muzzle Velocity (55gr)	Case Weight vs. .22-250	Primary Use
.223 WSSM	4,600 ft/s	+60%	Varmint/Predator Hunting
.223 Remington	4,000 ft/s	Baseline	Military/Sport/Hunting
.22-250 Remington	3,680 ft/s	Baseline	Varmint Hunting
.308 Winchester	2,700 ft/s	N/A	Game Hunting

Why It Matters

Extreme Velocity: The .223 WSSM stands as the fastest .22 caliber cartridge in production, delivering unmatched velocity and flat trajectory for long-range varmint hunting applications.
Engineering Innovation: The cartridge demonstrates advanced case design principles, with thick walls and reinforced construction that allows safe operation at significantly higher pressures than conventional .223 rounds.
Performance Trade-offs: While velocity performance is exceptional, the high-velocity design inherently causes rapid barrel erosion, reducing barrel service life compared to lower-velocity alternatives.
Market Niche: Despite impressive ballistic performance, the .223 WSSM has maintained limited market adoption, with shooters often opting for established calibers offering similar performance with longer barrel life expectancy.

The .223 Winchester Super Short Magnum remains a specialized cartridge for dedicated varmint hunters and long-range shooters willing to accept shorter barrel life in exchange for superior ballistic performance. Its introduction marked Winchester's commitment to extreme velocity platforms, though the cartridge ultimately occupies a narrow market segment within the broader rifle ammunition landscape.