So someone held a gun to his head and repeatedly fired blanks.

你是说有人拿枪指着他脑袋连续放空枪
That's incredibly risky,

这极其危险
especially considering the margin of error

特别是考虑到握着枪
when you're holding the barrel of a gun

对着别人的颞骨时
to someone's temporal bone.

产生的误差幅度
The discharge alone can cause the skull to shatter.

单是气流的射出也可能导致头骨粉碎
Which means not only did this person

这意味着这个人不仅是
want to put the fear of god into Gavin,

想让加文产生恐惧
but he knew exactly how to do it without killing him.

还清楚如何在此过程中不伤他的性命
This poor kid was tortured.

这可怜的孩子被虐待了
Or trained.

或者是被训练
What if whoever did this wanted to make sure

如果做这事的人是为了确保