ps3xbox360 It appears that young cazadores are immune to time bombs and can be immune to tin grenades. Sometimes they are completely unharmed when the adults are killed in the same proximity.
ps3 Adult cazadores may be immune to damage from a tin grenade.
xbox360 In the Silver Peak Mine, sneak-attack killing cazadores with long-fuse dynamite does not count towards the achievement.
pcps3xbox360 As long as the weapon you currently have out is a tin grenade, long-fuse dynamite or a time bomb, the kill counts towards the challenge. (Example- You throw a plasma grenade into a crowd of cazadores, and switch your current weapon to a long-fuse dynamite before the plasma grenade explodes; if the plasma grenade kills any of the cazadores while you have a long-fuse out, it'll still count towards the challenge. Note: Young cazadores still appear to be immune to damage in this instance, despite attacks coming from frag grenades, detonate plasma mines and plasma grenades that damaged nearby cazadores)
pcps3 The above bug also works the other way around. When killing a cazador with a tin grenade or long-fused dynamite, it does not count towards the challenge if you switch to another weapon before the explosion. This is also true if you threw your last Explosive, since you are then unarmed.