So I'm having a lot of trouble with the 'I've got it!' achievement for catching a knife with your face. Any tips for getting this one? My current strategy is to cast a portal, turn around, and throw the knife backwards, using smooth locomotion to fine tune my position

The arrow has gone right between the eyes more than once without unlocking, and I know the distance is great enough because I got the 'Single player Sportsball' achievement with the same method

Any tips would be greatly appreciated, this is the last achievement really holding me back from 100%