Max Payne 3
67 Achievements
Express Checkout
Kill 4 players within 3 seconds in the Imperial Palace.
How to unlock the Express Checkout achievement in Max Payne 3 - Definitive Guide
Unfortunately I became a legend last week, so I don't have the double weapon burst available, but since level 48 I used that burst at the 3rd level and I killed several time 4 or more opponent in only 1 second, since the grenades explode at the same time. If you want to obtain this cheevo legit use this method and you won't have any problem ;) The method I explained is only 1 of the 1000 possible methods that you can use ;-)
With this method not only are you unlocking your achievement but also putting work towards your grind for grenades. Any weapon that explodes works great but I would highly suggest regular grenades because of the crazy physics in this game. Any questions please don't hesitate and if you down vote please say why.
If you want to go for this legitimately, the easiest way to pull this off is to unlock the Weapon Double Dealer Burst perk which is available at level 48, when this is triggered at level 3 all the enemies grenades will instantly drop and explode. When you trigger this you need to be in the line of sight of at least an enemy player and be ready to kill them, hopefully causing a chain reaction to the other players on the team and blasting them all.
Although that last method still seems quite challenging, this is a challenging achievement therefore you can always boost it by getting together 8 players again and start up a public Team Deathmatch game. Then gather 4 enemy players in a small area like inside the empty swimming pool and either blast them with an RPG or chuck a grenade.
Mode: Remainer, Payne's Killer
Everyone goes to the pool at the Imperial Palace, two players become Max and Pasos. Max or Pasos throw a grenade at 4 people and get a trophy. Then others become Max and Pazos and do the same.
This can only be done in an open game; it is best to start the mode in free aim so that no one interferes.