Just wondering if you attach a silencer if it reduces your damage? I was curious because I attached a silencer to the sniper gun and cannot get a 1 shot kill even when its a head shot and they are not in armor mode. Has anyone else experienced this or do sniper guns always require 2 to 3 shots to kill?

Silencers decreases your range. So in a way it lessens your damage output at long range.

EDIT: my post reflects the headache that is currently killing me, but I am too lazy to fix it and explain how range factor works, mainly because English isn't my native language.

My experience with the rifles, with or without the silencer, an alien can be 1 hit killed with a headshot so long as he isn't alerted to your presence. I could be mistaken with the silencer but I seem to recall getting some. Without the silencer a normal Ceph takes 2 body shots alerted or otherwise. With the silencer it seems like 3-4 shots. The armored Ceph(red glowing ones) take way more with the silencer and 4-6 without.

The big tank looking ones(not the great big ones), I've never counted how many it takes.

Weapon damage is generally given in two values. Max damage and minimum damage. A weapon begins at max damage, then after a certain range it degrades until minimum damage is reached. The bullet then continues to travel at minimum damage until it hits something. Suppressors reduce max damage and min damage range.

In the case of the DSG-1 it has only one damage value meaning it deals the same damage regardless of range. Although I have no proof of this, its just an educated guess, but I would assume the DSG-1 suffers a damage hit unlike the rest of the weapons which merely get a range reduction.