Oddly enough, it’s chambered in 12.7x55mm. I’m guessing the Russians wanted something to compete against the .50 Beowulf in the heavy and slow stopping power category. But the .50 Beowulf can be deployed from the standard AR-15 platform. I would imagine a specialized rifle with a specialized caliber is a bit too much of a niche to make a real market. The ridiculous looking revolver pictured in the above link looks even more impractical.