Off the web site:

TRIPLE SEVEN MAGNUMS give you the capibility to make a longer shot and deliver more energy to the target. If you've shot Triple Se7en products before, you can expect the same easy clean up with no rotten egg smell. Using two Magnums you can achieve an additional 200-250 feet per second (fps). This normally results in muzzle velocities of approximately 2,000 fps.
While we are confident there are other muzzle loading rifles and saboted bullets that will acheive the 2,000 fps velocity, the ones listed below were tested by Hodgdon or the manufacturers and met or exceeded 2,000 fps with 2 (two) Triple Se7en Magnums.