How do you kill Barrett in Deus Ex Human Revolution is there a secret way that kills him quicker or do you just keep shooting him

It took me ages but this way worked for me. Firstly lets imagine that facing Barret at the start is facing North. As soon as the cut scene ends, quickly run south behind the crates and crouch down away from his shooting. Again quickly, move around the boxes (still crouching) and pick up the gas canister. Now throw this at Barret making sure you do not miss. This will slow him down for a few seconds. Now run to the south east. Just before you enter the small room pick up the flammable red barrel. Again throw this at Barret making sure you do not miss. Now run back into that small room and pick up the grenade. Now crouch down behind the crate on the north side of the small room. As Barret enters throw the grenade at him. Now still crouching behind these crates you will need to time when he stops shooting, then peer round the crate and shoot him as many times as possible with your most powerful gun. You will need to do this a few times until he dies. Make sure you have plenty of pain killers etc. as he may throw grenades at you.