M4A1-S

Play angles where enemies appear one at a time — the 20-round magazine punishes multi-target sprays.

Abuse the silence: shoot through smokes and from off-angles, because no tracers means enemies can't instantly locate you.

Tap and two-shot burst at range instead of spraying; the M4A1-S has the best standing accuracy of any full-auto rifle.

Count your bullets and reload behind hard cover only — the 3.1-second reload with 80 reserve rounds leaves no margin for panic reloads.

At very long range, aim head-height only: the 0.94 range modifier makes body-shot kills need four to five hits.

Swap between M4A1-S and M4A4 per map in your loadout — long-range maps favour the A1-S, tight retake-heavy maps favour the A4.