Impact Hits

What knoffles says.

Funnily enough, the Resolving Unusual Attacks box on BRB p. 42 is silent about the distribution of the hits. This was clarified by BRB Official Update Version 1.9, p.8:

Q: When hits, other than from shooting and close combat attacks, are inflicted upon a unit how are these hits resolved? (p42)
A: As per the ‘Resolving Unusual Attacks’ box. Note that all hits resolved in this way will count as shooting attacks for working out who is hit.

Hence:

BRB p. 93: "A champion cannot normally be targeted by enemy shooting attacks — he can only be removed as a casualty if there are no other rank-and-file members of his unit left (not even the standard bearer or musician)."

BRB p. 99: "'Normal' shooting attacks — by which we mean to say shooting attacks that use the firer's Ballistic Skill — cannot hit a character in a combined unit if there are five or more rank and file models from the same troop type (including musician and standard bearer, but not the champion) left in the unit. We assume that the enemy cannot pick the character out. All hits are allocated onto the unit's rank and file models.

If there are fewer than five rank-and-file models left in the unit (or the character is of a different troop type) there is a chance that any characters in the unit could be hit — the controlling player decides who is hit, but must allocate one hit on each model before he can add a second hit on a model; he must allocate two hits on each model before he can allocate a third, and so on."

Note also BRB Official Update Version 1.9, p.3:

Page 71 – Special Rules, Resolving Impact Hits.
Add the following sentence to the end of the third paragraph:
‘“Look Out Sir!” rolls cannot be taken against Impact Hits.’