Now, I haven't seen this movie, I admit (already sensing the trouble I'll be in for that statement), but I'm definitely getting the idea of what the movie was about.
The best place I can see this being set in is Los Angeles - major crime problem in some parts of town (pretty much everything between USC and Long Beach is infamous, with some justification), wealthy in other areas. Best time would be mid-1990s.
Storyline:
The Rodney King riots are a lot bigger and uglier than in OTL. The massive mess that follows forces the police into almost impotency, as crime gangs move in across most of LA, with police actively helping the gangs in some cases.
As Los Angeles in many areas falls into major crime problems, many local residents realize that they cannot rely on the police to defend them. Hence, they go to buy guns for themselves, and in the process ask Chris Adams, a former Army Ranger, to lead them. Adams turns them down, syaing that one man is not enough to stop the criminals. He eventually does recuit six other men to do the job - Vin, Bernardo, Lee, Harry, Brit and Chico.
The Seven begin to bond with many of the local residents, and begin to move from paid defenders to being both locals and in many cases lovers with the local population. The local big shot crime bosses, realizing that the local population has found some reliable, dangerous bodyguards, decides to try and drive them out.
Not expecting a full-blown war, the group decides to stay and finish the job rather than run away. They are assisted by a group of former local gangbangers, who provide both knowledge and firepower. They make a raid on the gangs' main stakeout to try and hit them before they attack, but this fails. They return to the local territory, only to be escorted out by the gangbangers.
The group decides that they have to finish this one way or another and returns to fight. The local residents realize that they can help and join in with whatever firepower they can get their hands on, and the police, realizing how bad this has gotten, now decide to intervene. They are unable to do much but clean up the mess, however.
Chris and Vin leave afterward, stopping only to pay respects and the graves of their fallen comrades.
Characters:
Chris Adams - Dwayne "The Rock" Johnson (Yul Brenner)
Vin - Mark Wahlberg (Steve McQueen)
Bernardo O'Reilly - John Travolta (Charles Bronson)
Lee - Rick Yune (Robert Vaughn)
Harry Luck - John Savage (Brad Dexter)
Britt - Sean Bean (James Coburn)
Chico - Benjamin Bratt (Horst Buchholz)
Rick Calvera - O'Shea "Ice Cube" Jackson (Eli Wallach)
Hector "Hilario" Lopez - Yul Vazquez (Jorge Martinez de Hoyos)
Petra - Jordana Brewster (Rosenda Monteros)
The Old Man - Earl Boen (Vladimir Sokoloff)
Ramon Sotero - Jason Manuel Olazabal (Rico Alaniz)
New Characters:
Capt. Peter Marren, LAPD - Hugh Laurie
Lt. Paul Victor - Henry Rollins
Daniel "Danny Boy" Jackson - Gary Dourdan
David "Little Rocker" Stanley - Robert Guy Torry