What is the most powerful BB gun?

If you are asking about airguns in general not just BB guns, but Pellet guns also. The family of PCP air guns. (Precharged Pneumatic Guns (PCPs) these use a Scuba tank to charge the rifle. They can shoot up to a 50 cal bullet and bring down a Moose. As for BB guns alone most will fall into the under 500 feet per second group. Where Pellet rifles can exceed 1000 feet per second. BB guns/rifles are not as accurate as pellet guns/rifles. Because BB guns use a smooth boar barrel where pellet guns use rifling in the barrel.