Gangster Squad centers on Mickey Cohen (Sean Penn), an ex-boxer who’s trying to be the main mob boss in L.A. in 1949. Police Chief Parker (Nick Nolte), an honest cop who surreptitiously assigns his top sergeant, John O’Mara (Josh Brolin), a fearless World War II vet, to disrupt Mickey’s plans and send him packing. John then puts together a motley posse that includes one of the department’s biggest playboys (Ryan Gosling), a sharp shooter (Robert Patrick) and his sidekick (Michael Pena), and a street-wise detective (Anthony Mackie). While John provides leadership and overall muscle, Conway Keeler (Giovanni Ribisi) is the brains of the operation. He places a wiretap in Mickey’s home that then enables them to target a few of the mobster’s establishments and disrupt his operation. The cast is terrific, but the movie centers so much on the machine gun culture of the time period that its release date was postponed so that it would come out well after the Aurora, Colorado shooting. And that’s part of the problem. In the place of character and plot development, we get a series of dramatic, slow-mo shootouts and montages of gangsters and cops going at it.