Due to its weight, the TSMG rises very little. What happens is that when the gun is fired from the shoulder, there is enough recoil that the shooter's shoulder moves back, pulling the gun back and up. When this tendency is overcome by leaning into the gun, climb is minimal, especially with the Cutts comp.
Guns like the STEN and M3, which have a bolt that is heavy relative to the gun, stay down because the forward slam of the bolt compensates for the rearward motion under recoil. They really do sort of "rock."
Jim