Guns are in such short supply at the Border Patrol that one agent told FoxNews.com 400 agents share just 100 rifles at his station.

The lack of weapons is more than just a nuisance, according to law enforcement authorities, who say each agent should be able to calibrate his or her gun to individual preferences, a process they call "zeroing."

“In the year 2015 we shouldn’t be talking about using pool rifles.”

- Chuck Haggard, firearms instructor

“We are left to check out rifles that were unzeroed to us," a border patrol agent told FoxNews.com. "This practice needs to be outlawed, as it could cost someone their life."

“Zeroing”includes setting the rifle’s sights to one's eyes and adjusting for any tendencies of the gun, like a bias to shoot towards the left or right.

"It is a major problem when I cannot be absolutely certain where my round will hit in relation to my point of aim," another border agent told FoxNews.com.

One agent noted that the type of work he does could easily put him in a position where he needs a reliable rifle.

"Imagine you are out in the mountains of Arizona, walking a trail known to be used by drug smugglers.As you walk up a ridge, a group of smugglers crest over the mountain on the same trail 100 yards away - coming straight toward you, armed with AK-47s," he said.

The situation recently became more aggravated as the Border Patrol has gone through its arsenal and weeded out more than 2,000 M4 carbine rifles that they said had the potential to malfunction. One agent said that in his station, fewer than 100 rifles are now shared by 400 agents.

Asked by FoxNews.com for comment, a spokesman for the border patrol officers’ union said he hears this complaint often and that the union is now in talks with the Border Patrol to make sure each field agent has his own rifle.

“They are receptive to the idea… hopefully we are going to get more rifles into the field. It is not a weapon that should be shared among agents, because it is a precision weapon,” Moran said.

U.S. Customs and Border Protection, the agency that runs the Border Patrol, did not answer questions from FoxNews.com about whether it was safe to arm agents with communal “pooled” guns but said that the agency is committed to giving agents what they need.

“CBP is committed to ensuring its frontline agents have access to the equipment and service weapons they need to enforce the nation's laws and protect themselves and others against those would do them harm,” CBP spokesman Carlos Lazo told FoxNews.com.

Firearms experts told FoxNews.com that having an un-zeroed rifle makes a big difference.

“It’s a fiasco. The idea of ‘pool rifles’ is typically something administrators get into when they are trying to save money,” Chuck Haggard, a firearms trainer who is a former SWAT team leader and shooting instructor for the Topeka, Kansas, police department.

Haggard said that the Topeka police department once used pooled rifles, but eliminated them about a decade ago in favor of giving officers their own assigned rifles.

He said that doing so made things safer, based on tests he conducted on a range with expert shooters. Often, Haggard said, the marksmen with rifles that were not personalized to them missed easy targets.

“In the year 2015 we shouldn’t be talking about using pool rifles,” Haggard said.

“The entire point of patrol rifles is to have a precision weapon system. Pooled rifles are a sloppy way to do business and dangerous to bystanders,” he added.

Other firearms experts agree.

“Agents need to know where their issued rifle is hitting. By using pool rifles, agents are in danger of not hitting an assailant and also in danger of shooting a noncombatant,” said a former Marine who was one of the first to blog about the issue.

One agent suggested that if the agency doesn't feel it can afford a rifle for each officer, it should at least allow them to carry their own rifle on duty. Moran said that idea has problems, however, and that it would be better to just have more rifles for the agents.

“It opens up the agency to too much liability,” Moran noted.

“Also, in a combat situation, should an agent go down and someone is forced to use somebody else’s rifle -- you want to be familiar with the type of rifle,” he said.

One agent said that he thought the current situation exposed the Border Patrol to more liability.

"What happens when an agent shoots the wrong alien, smuggler, or God forbid another agent because the gun's sights are so far off?" he asked.

“My hope is that that practice will be blacklisted and outlawed… that no other agent or officer will have to gamble with their life based on how some other random individual treated that weapon system,” the agent said.

The author, Maxim Lott, can be reached at maximlott.com or at maxim.lott@foxnews.com