He felt a rifle barrel in the small of his back.

The men were not behind cover looking out over their rifle barrels.

When they looked up it was into two rifle barrels.

His eyes opened and he followed the rifle barrel to me.

At once she was looking straight down the barrel of his rifle.

Slowly he brought the rifle barrel down and stood looking across at Michael.

She looked over her shoulder at the two rifle barrels.

Tom was about to pull the rifle barrel back in when he saw something else out there.

"A mess someone wanted to clear up at the end of a rifle barrel."

For instance, someone might be told to clean the barrel of their rifle.