When one player has gotten a weapon that another desires, go to Club: Stakeout 
on Agent mode. Drop that player's weapon to a second player. Have any one of 
those players continue through the level normally. If done correctly, the new 
player can have the weapons in less than three minutes. The faster way through 
the level is to run in the club after the first objective is complete unarmed, 
and rush to the very top to Jack Dark.