Did old muzzle loading guns have more power and velocity than modern guns?

Did Old muzzle loading guns like muskets, blunderbuss, etc have more velocity and power than the bullet cartridge type guns? I know old muzzle loaders were extremely inaccurate, but was it because it was basically a handheld cannon? When modern bullets were introduced did it reduce power but gain accuracy? Or are modern bullets all around better than ever grooved barrel muzzle loaders?