The Silenced AR-15 does around 13-15 damage per shot. It has 30 bullets in a clip and takes 1 second to reload.
The Silenced AR-15 can only be found in chests, and can only spawn in Mythic Rarity. The Silenced AR-15 is not silent, but is noticeably quieter than other ARs. With its high attack compared to other ARs, it is capable of taking down M4, SCAR, and AK users. Despite the Scoped M4 doing 2 - 4 more damage, the Silenced Ar-15's ridiculous ROF and dmg + knockback is capable of beating a Scoped M4, but only if you land your shots.
Be careful when using this AR in the early-medium stages of the game, as you will be targeted if enemies see you holding this gun. They will be desperate to get it for themselves and will stop at nothing to kill you.
Strategies
Try to corner the Scoped M4 in a house or building, then run in and spray them to death. The Silenced AR-15 is also almost better than almost all SMGs, having a higher lower DPS, but has the same highest DPS. The only SMGs that it could lose to in close quarters would be the P90 or the Vector.