A federal judge ordered prison time for two men who admitted to using wild horses as target practice but sought leniency Wednesday, telling them that "drunken and boneheaded is not an excuse" for the crime.

"I keep thinking about it, and I keep coming back to the senselessness of it," said U.S. Magistrate Judge Robert McQuaid Jr., who rejected defense lawyers' plea for probation and sentenced Joshua Keathley and Todd Davis to six months each in prison.

"I might feel differently if you were 18-year-old kids, but you are not 18," he said during the hearing in Reno. "You need to have some time to think about it, alone."

Keathley, 36, and Davis, 45, both of Lovelock, pleaded guilty in June to shooting the mustangs. Keathley said the two had been drinking and were looking for places to do some trapping when they came across the horses in the rangeland about 150 miles northwest of Reno.

In seeking the lighter sentences, Keathley's lawyer, John Springgate, told the judge that "there is no question it was senseless."

"This is boneheaded, drunken behavior," he said, but added "we should distinguish between boneheaded, drunken, stupid — which this was — versus a significant criminal act."

The judge replied: "Drunken and boneheaded is not an excuse."

Assistant U.S. Attorney Sue Fahami had sought a year in prison for each man. She said one of the most "disturbing and "cold-hearted" parts of the crime was the shooters' total disregard for the animals after they were shot and left to die.

"Any hunter knows that when you go hunting, you want a clean shot" that kills the animal quickest, said Fahami, a former prosecutor in northeast Nevada's rural White Pine County.

The case prompted outrage from horse protection advocates around the world.

"The federal prosecutor's fight for a stiffer sentence is a red flag to those who see Nevada as their own private shooting range," said activist Terri Farley, Reno-area author of the popular "Phantom Stallion" series of children's books. "Six months in prison is pale punishment for robbing wild horses of their freedom forever, but these two may think before pulling the trigger again."

Daniel Bogden, U.S. attorney for Nevada, said Wednesday it proves "we take the harassment and killing of wild horses on public lands in Nevada very seriously."