You may have one at home right now: a gun.    

Would you use it to stop someone who’s stealing from you or from your neighbor?

It’s what happened earlier this month in Pasadena, but using deadly force can have repercussions that could cost you far more than whatever it was the thieves were after.

It’s one thing to know how to shoot a gun at a target, but what if you were shooting at a real person?

It’s what Joe Horn did when he said he saw two men burglarizing his neighbor’s house in Pasadena.

“I can’t take a chance on getting kill over this,” he was heard saying on a call to 911. “I’m going to shoot. I’m going to shoot.”

The deadly blasts from his shotgun caught on the 911 tape.

It’s one thing to be for the right to bear arms, to protect you or your property. But what if you really did it? Shooting someone is about as serious as it gets, legally, financially and even emotionally.

Take Jerry Casey.

One night 13 years ago, he thought a thief was trying to steal his pickup from in front of his home in north Houston.

He got his rifle and fired, killing the man who was in a wrecker and turned out to be a repo man just doing his job.

A grand jury though did not indict Casey, but eight months later, he nonetheless killed himself, citing the repo tragedy in a suicide note.

In cases like these where it’s not a clear cut case of self-defense, the legal costs can soar.

“The average price today to be represented before a grand jury is about $8,000,” Greg Smith said. “If they no-bill you, you’re still open to civil litigation.”

Smith isn’t a lawyer. He’s an instructor for people wanting to get licensed to carry a concealed gun.

“The bottom line is, I don’t want them to ever have to use their gun,” Smith said.

He said after he explains the legal and financial liability for shooting someone, the majority of his students decide not to pack a pistol.

“They realize going through this class all the repercussions, all the implications,” Smith said.

“There’s an attorney attached to every bullet you fire,” lawyer Tom Nixon said.

Nixon is a lawyer. He’s also a card-carrying concealed handgun owner and has a company that provides licensed gun owners legal help for $10 a month.

“And if God forbid, you ever have to go to trial, we defend you at trial,” Nixon said.

How much would that cost?

“For murder? Probably between $75,000 and a $100,000 because you’re going to have to hire expert witnesses, and they’re never cheap,” he said.

You can get free advice on his Web site:

Like, “Do not tell the 911 dispatcher” any details about the shooting because it’s “being recorded” and will be used “against you.”

And instructor Smith said, “If someone breaks into your house, you don’t go hunting for them … defend yourself if necessary, but hide or run.”

The point: Minimize the chance you’ll have to shoot because pulling the trigger can carry extraordinary costs.