I call BS on that...The faster a bullet is moving, the faster it expands...

I have a 1100 slug gun, have had it since '75...I still use my .243 in the woods, doesn't matter if they are 30 yards or 300, the .243 will drop them...The trick to using a high powered rifle in the woods is to have a good scope, adjusted properly so you can avoid brush...You might also consider using a stouter bullet because at close range and the higher velocities the bullets will come apart quicker, not a problem with good hits, because the deer drop quicker as well...