The NYPD flooded the city with extra cops last week to combat a surge in violence — but Gotham still had more than double the number of shootings it experienced that week in 2014.

During the first week of “Summer All Out,” a crime-fighting initiative that moved about 330 cops from their desk jobs to violence-plagued neighborhoods, there were 43 shootings that left 53 people dead or wounded.

During the same week in 2014, there were 21 shootings.

The summer program was even started a month early this year to try to get a jump on the problem. So far, though, it’s done little to help.

“It’s not going to abate the problem,” a police source said grimly.

While the redeployed cops mostly hit the streets at night, when most shootings occur, “These are not cops who are going to bring in gun collars or drug collars, because they didn’t do it in the first place,” the source said.

“These are police officers who were working inside. Their street skills are limited to begin with, their ambition and drive is probably mediocre at best, and I believe it will have little effect, other than the fact you’ll have 300 uniformed cops standing on street corners in some high-crime areas.”

The feds will take a more hands-on approach to the gun violence now that they have lowered the criteria necessary to prosecute criminals. The Bureau of Alcohol, Tobacco, Firearms and Explosives may investigate gun cases involving suspects with just one prior felony conviction, rather than the previous requirement of two felonies.

Nineteen of last week’s shootings happened in The Bronx, where 23 people were hit by bullets from June 8 through Sunday. Six were shot in The Bronx for the same week in 2014.

Meanwhile, murders were up 40 percent for the week, with seven killings citywide — five of them in Brooklyn alone.

Mayor Bill de Blasio said Monday “Summer All Out” worked wonders last year to contain crime in several of the worst precincts and needs more time before the effects are felt this year.

“ ‘Summer All Out’ is a few days old,” he said. “We are having a challenge right at this moment with some of the recent crime numbers . . . [but] I think with each passing day, with each passing week, we’re going to feel the effects of it more and more.”

Additional reporting by Larry Celona and Jamie Schram