Hits scored by a weapon with the Precise trait are allocated by the firing player, not the player who controls the target Detachment. All other rules for allocating Hits still apply (i.e., the firing model must be able to see a model allocated a Hit, wounded are allocated Hits first, etc.).
Building an army? Create, validate and share your list with New Recruit, army builder for Horus Heresy: Legions Imperialis and many more games.
Try the builder