Legiones Astartes (Iron Warriors) Wrack & Ruin: When a model with this special rule makes a Shooting Attack or Melee attack targeting a model with the Dreadnought, Automata, Vehicle or Building Unit Type it gains +1 to the Strength of that attack.
Precision Shots (X) If a model with this special rule, or attacking with a weapon with this special rule, rolls equal to or higher than the value in brackets when making a To Hit roll as part of a Shooting Attack, that shot is a ‘Precision Shot’. For example, if a model with the Precision Shots (4+) special rule rolls a 4 or higher when making a To Hit roll, then that attack is a Precision Shot.
Wounds from Precision Shots are allocated against a model (or models) of the attacking player’s choice in the target unit, as long as the target model is in range and line of sight of the attacking model, rather than following the normal rules for Wound allocation.
Note that Snap Shots and shots from weapons that scatter, or do not roll To Hit, can never be Precision Shots.