Headshots while in Stormraven

Everything flared white and yellow as payloads detonated on contact. From his place at the hatch, Karras saw t’au bodies cartwheeling off into the dark, falling to the courtyard, their combat fatigues ablaze. A few were left alive on the rooftop, stunned and deafened. They staggered blindly, disoriented by the explosions.
Karras took aim and added his own fire to that of the nose-mounted bolters. He picked them off with ease. Heads snapped backwards. Rounds detonated within alien skulls, blowing them apart. The pilot gunned the engines and the Stormraven surged forward.
...
Solarion squeezed the trigger.
His rifle kicked.
One moment, the Fireblade leader was standing on the wall, yelling and barking like a mad dog, frantically trying to coordinate his squad’s fire on the Stormraven overhead. The next moment, he had no mouth to yell with. The round obliterated his lower jaw and then punched through the back of his neck with such force that it tore the skull free. The body dropped to its knees, then pitched forward, landing awkwardly, limbs at angles, hands still gripping his carbine.
...
As the Stormraven levelled out, Solarion sighted down his scope, zeroed in on one of the t’au with the rail rifles and squeezed off another perfect shot. The round took the target in the chest, hitting like a meteor.

Shadowbreaker