Begin your new game and submit the name Shooterman . All levels and characters will be unlocked.
Beat the 3rd mission in the story mode.
Beat the 2nd mission in the story mode.
Beat the 4th mission in the story mode.
It should take about four to seven seconds for a grenade to explode. In that time, shoot like crazy. For easier aim (unless they directly in front of you), zoom by pressing R3.
Helghast assualt rifle
Used by Helghast infantry, it is fast with a large clip, and with a low recoil it's quite devestating. Plenty of ammo around since almost all Helghast carry this gun in the earlier levels, and some in later levels as well. As well as being a Helghast gun this is also Hakha's gun too.