This is not a bug, silencers increase bullet speed and range.

https://answers.yahoo.com/question/index?qid=20090617224540AALJWPL

Suppressors are used with subsonic rounds, which means they travel SLOWER than the speed of sound, therefore DECREASING range and increasing bullet drop.

Except there are no subsonic magazines in the game currently. So attaching a suppressor to your gun will lengthen the barrel, and cause standard ammunition to travel further.

yes, there are mufflers step-up speed bullets (special), must be and standard (lowering speed bullets). A muffler (step-up speed of bullet ) needs to be made accessible for a few rifles,but not for all. Otherwise all will carry mufflers, if he increases speed of bullet and diminishes a sound.

It's up to the designer of a mission to decide what people have access to. If people are given the choice to equip a bunch of powerful stuff, they'll do it. Regardless, with normal ammunition, attaching a suppressor will make the rounds travel further. The ballistics work as intended.

Disadvantages of silencers ingame are that they add weight and inertia to the weapon, which has an effect on fatigue weapon handling.

The increased muzzle velocity also changes the ballistics in a way that the Page Up/Page Down zeroing no longer matches the ballistic arc programmed for that weapon, so all bullets will hit slightly above the crosshair even if you zero the sight to the range that the target is at. This means you have to hold the crosshair of the scope lower down than normal and makes shooting at long ranges more difficult than before, unless you're very well practised.

If we have no subsonic ammo then why are some rounds not breaking the sound barrier?

automatic with a silencer has a greater speed of a bullet, the damage too?

IIRC in various mods there is SD ammo available so if u want it you can get it.

And yes supressors should increase muzzle velocity, they also should increase a bit rate of fire of some wapons.

Most of the disadvantages of running a suppressor on a weapon are related to wear on the weapon and overheating, Arma 3 currently has no built in simulation of overheating. In real life firing a weapon with "hot" ammo out of a suppressed weapon will indeed slightly increase muzzle velocity, but its still going to be very loud. At best you're going from "gunshot" to "car backfiring"

Originally attaching a suppressor would magically make your gun act like it was loaded with subsonic rounds, which is what actually provides the decrease in damage and range video games associate with Suppressed weapons. This was removed because it was dumb for your ammo to magically change powder loading.

But it was only half done, so right now you have a situation where the ballistics of firing a hot load out of a suppressed weapon are done right, but the sound simulation isn't. But the problem is that if you do the sound simulation right, you're going to get a bunch of people either complaining because their suppressor "isn't working" or complaining because Subsonic rounds have crappy ballistic performance.