Normally this play is removed with pads. Put thicker ones in the sides and thinner ones in the front or arrange them in whatever combination gets even play all the way around. But, you've probably already tried this, so, you may have to experiment with helmet manufacturers to get one that has a basic shell shape that seems to fit your head. They are all a little different. I find that Bell fits my head well, while others often don't have the fore to aft distance I need.