M4A1 Silencer is one of the earliest assault rifle variant of the M4A1, spanning its own line of "Silenced M4" series.
This weapon is just a regular M4A1 fitted with a black silencer, making it possible to fire without causing much noise and giving tactical espionage in matches. It is very useful in Ghost Mode as players could spray randomly without disturbing their teammates, while they can still be able to hear Ghosts' breath and footsteps.
In most CF versions, this gun comes with an upgraded ammo capacity (+5), while in some other it has normal ammo capacity instead.
- Early models of M4A1-S has two separate parts, the normal M4A1 Model and the Silencer. This explains why certains M4A1-S can have the silencer not painted (Such as M4A1-S Mori), and certain beta models have no silencer at all (Like M4A1-S Sakura).
- In CF Philippines, players can receive a permanent M4A1 Silencer (M4A1-Adv) by completing the Elite Final Badge.
- The M4A1 Silencer have 2 HUDs, 1 original and 1 fixed, smaller one. The second HUD officially replaced the first after the M4A1-S Blue Pottery was released.
- In the first years when CrossFire launched, all M4A1 variants had a moving animation: It will bob up and down when players move, this does not affect the weapon's overall performance. By some reason, this effect is removed out of game for 5 years, and now SmileGate had decided to bring it back but some players find the animation annoying and distracting. Oddly enough, only M4A1 Silencers with the original HUD (old model) received the aforementioned animation.
- This problem occurred during the first time when Accessory System has been added in to CF CN, and Tencent was too careless to add an old animation on this guns with a ring model, after that Tencent changed it back, other servers used this model thought they didn't have Accessory System at that time. So far, CF VN still use this animation.
- The M4A1 Silencer has more variants than any other weapon in Crossfire.
- Also, M4A1 Silencer has most VVIP variants than any other weapon. Same goes for their reskinned variants (Noble Gold, Imperial Gold, etc.).
- This gun have two variants in CF VN, the first one is temporary and can be rent in the Item Shop or obtained as the junkie prize in Black Market, correctly named "M4A1-Silencer" with no ammo boost, while the second one is in the Training Camp as the pick-up weapon during the Shooting Range and later as one of the new basic weapons for newly-created accounts, named "M4A1-Adv" with +5 ammo boost.
- In the artwork of Ixions, SWAT 2.0 and its Camo variant for the GR side, they show the characters holding the M4A1-Silencer with a folding stock which is only used in M4A1-Custom and variants.
- M4A1-S is now one of the fundamental weapons in CF China, CF Indonesia, CF Vietnam & CF West, as they implement new weapon system for newly-created accounts.