Some comments sire
~Demolition is for a sniper game play, atomic bullet is more useful in very way level 7~10 is nice for the slow.
~ Swigers level 3 is for max stun + damage, level 4 is for the max range + damage, level 5 will just give higher damage, so mostly people just get it at least level 4 for the maximum stun duration and the max range of the skill itself for rotation setup