Remington Hypersonic Steel
Remington's Hypersonic steel achieves velocities of 1,700 feet per second thanks to a wad that more or less turns the shell into a two-stage rocket. A hollow stem on the bottom of the wad extends down into the powder and over the primer. The primer ignites only the powder in the stem, pushing the wad down the barrel before the rest of the charge ignites. With more space in which to burn, the powder doesn't generate dangerous pressures, even as it achieves velocities that were previously unimaginable with 1 1/4- and 1 3/8-ounce payloads. The wad exits the muzzle as an intact shot cup, splitting open in flight to release the pellets, which get to the target in a hurry.
I had a chance to shoot a lot of HyperSonic in Alberta when it first came out. These cartridges were available only in 2s at the time, and they performed superbly on snow geese, white-fronted geese, and medium-sized Canada geese as well as ducks. Remington is a proud partner of Ducks Unlimited. remington.com