San Francisco cops dodged a real bullet the other day when one of their AR-15 rifles wound up in the hands of an East Oakland gang after being stolen out of the trunk of an unmarked police car.

The prospect of a police semiautomatic rifle being used in a violent crime prompted a Code 3 response once officers discovered the theft last weekend South of Market.

Police Chief Greg Suhr immediately put out word to start questioning every street source they had.

"No resources were spared," Suhr said.

Asked exactly how they traced the rifle, the chief told us that "it wouldn't be in the best interest of future cases to give away trade secrets."

Other law enforcement sources, however, said the department caught a break almost immediately when an undercover cop working his informants in the Bayview heard about a stolen police rifle showing up in Oakland.

Soon, Suhr himself was on the phone to Oakland Police Chief Howard Jordan, whose department promptly joined in the hunt.

Law enforcement sources familiar with the practices of San Francisco and Oakland police tell us it's likely they paid for the key information they got.

"We have a fund that pays for information on guns," says one longtime San Francisco police insider.

Oakland police spokesman Sgt. Chris Bolton would say only that police used "a number of investigative techniques."

Once the cops got an address, the Oakland SWAT team was brought in.

Police negotiators were then called to make contact with those inside the house on the 1300 block of 88th Avenue, urging them to surrender peacefully and to give up any weapons.

Other details about the raid have not been divulged, but we're told that there was a car chase at one point involving at least one suspect who fled.

Still, while as many as seven people were detained, there were no arrests - a clear sign, department insiders say, that they had a deal with somebody to get the weapon back with no questions asked.

In addition to the stolen police rifle, officers recovered a Ruger Mini-14 tactical semiautomatic rifle, a semiautomatic pistol, a shotgun, 1,000 ecstasy pills and other drugs.

As far as Suhr is concerned, "We got lucky."

Money drip: Last month's water-main break that flooded 23 homes in San Francisco's West Portal neighborhood was particularly nasty, but the break itself was hardly unusual.

The city reported 209 water-main breaks and about as many burst sewage lines over the past two years, and paid out claims and judgments in that period totaling $5.4 million.

Officials with the San Francisco Public Utilities Commission partly blame the city's aging infrastructure - noting that 200 miles, or about a sixth, of its water pipelines are more than a century old.

Some of its brick sewers date back to the 1850s.

The PUC says it's working to get a better handle on potential problem spots, and has identified 320 miles of "priority pipe" for replacement.

"Projections show we are going to hit a bump where the age of our sewer and water mains have reached their expected life," said PUC spokesman Tyrone Jue.

Judged: It's been eight months since Judge Paul Seeman went on leave from the Alameda County Superior Court bench after being charged with bilking an elderly woman out of her life savings - and he's still collecting his $179,000-a-year salary.

Seeman, as we reported back in July, is entitled to his paycheck - regardless of whether he works - until he's been convicted of a crime.

Well, the wheels of justice have been turning rather slowly in Seeman's case, in part because the first prosecutor had a stroke.

Seeman, 58, has pleaded not guilty to felony charges of elder theft and perjury. Authorities said Seeman befriended his neighbor in the Berkeley hills, then stole from her after obtaining power of attorney for her and her husband, who died in 1999. The woman died in 2010 at age 97.

Seeman's attorney was briefly in court the other day to deal with some technicalities, and his client has been ordered to report back April 18 for a plea and arraignment - but there's still no trial date in sight.

Given the complexity of the case, says district attorney spokeswoman Teresa Drenick, the time that's elapsed "isn't that long."

Table for one: San Francisco Mayor Ed Lee doesn't appear to be overly concerned that embattled Housing Authority Director Henry Alvarez is opening a restaurant in Berkeley after having stepped away from his job on "medical" leave.

"I'm not sure what the conditions of the leave are," Lee said Friday. "We just want to make sure he wasn't doing anything to violate any of his conditions on that leave.

"Otherwise," Lee said, "I think he's saying, 'Hey, I'm moving on.' "

The mayor added: "And for him at this point, part of 'moving on' is not receiving calls from The Chronicle except to celebrate when his restaurant opens."