Barrel SSC Challenger Achievement in Army of Two (EU)

This takes the longest out of the 4 DLC achievements simply as you only get a few barrels a stage. The fastest way to do this is to boost it with 3 others on the Warehouse 2 level. There are about 15 barrels right at the end of it that continuous respawn after about 20 seconds. If all four of you run to the end and then take it in turns to blow up the barrels (It only takes one shot as they are so close together) then you should have this in about 15-20 minutes.