The Weatherby Vanguard Obsidian SB is a bolt-action rifle chambered in 7mm PRC with a 20-inch threaded barrel. It has a 3+1 round capacity. The SB designation in the model name indicates the shortened barrel configuration. 
 

Key Specifications 

• Brand: Weatherby 
• Model: Vanguard Obsidian SB 
• Caliber: 7mm PRC 
• Action: Bolt Action 
• Barrel Length: 20" 
• Capacity: 3+1 
   

Detailed Features 

• 20-inch barrel with threaded muzzle 
• 3+1 round capacity 
• Bolt-action platform in the Vanguard line 
• Chambered in 7mm PRC for long-range capable cartridge 
• Compact overall length from the 20-inch barrel

Owners of the Weatherby Vanguard Obsidian SB in 7mm PRC appreciate the compact overall length that the 20-inch barrel gives the rifle. For mountain or backcountry use where a few inches of overall length matter when the rifle is slung or packed, the shorter tube is a meaningful trade-off. Most are satisfied with the velocity retention 7mm PRC provides even from the shorter barrel.

The threaded muzzle is consistently called out as a practical addition. Running a brake or a suppressor without an adapter is a basic expectation for this class of rifle, and the Vanguard Obsidian SB delivers that. A portion of owners do note that muzzle blast and felt recoil are more prominent at 20 inches with a hot magnum cartridge, especially without a brake.

The Vanguard platform has a reputation for reliable accuracy in the bolt-gun community. The Obsidian SB variant carries that reputation forward, though some wish the stock was more adjustable for length of pull given the diverse use cases the short-barreled configuration attracts.