All bows have hand shock. Until someone makes a bow that's 100% efficient, they always will.
Hand shock is the excess energy left in the bow limbs after the arrow clears the bow. It has no where to go so it pushes the bow forward/vibrates, etc. The heavier the bow riser, the more of that excess energy is absorbed. That's one reason why most recurves have less hand shock than most longbows. They're just physically heavier. Another is the limb design.
String type and arrow weight also influence hand shock as others have already pointed out. Heavy arrows absorb more of the bow's energy, thus decreasing hand shock. Fast flite strings, because they don't stretch as much as dacron, also reduce shock by dampening the limb vibrations more quickly, and in fact, reducing the modulation of the vibration. (Sorry Chuck, you have it backward re fast flite/dacron)
How tightly you grip the bow also influences perceived/felt hand shock. If you grip the bow tightly, you feel it a lot more than if you grip it lightly.
Finally, people have different sensitivities to/tolerance for hand shock. I've shot a lot of different bows in the past 50 years, and except for one very old Martin ML 18 longbow with very whippy tips, I've never found hand shock bothersome in any of them, including Hills and other straight longbows.