Quick Summary: The 5.56x45mm is the standard US intermediate cartridge. In the RHS/ACE3 environment, its effectiveness is entirely dependent on velocity and projectile construction.

These are the primary rounds found in modern US Army and USMC loadouts (Post-2010).

==== M855A1 EPR (Enhanced Performance Round) ==== * Visual ID: Bronze/Silver Exposed Tip * Best For: General Purpose Infantry The “EPR” is the current gold standard. It features a hardened steel penetrator that excels at punching through body armor and light barriers (wood/drywall). Community Note: This should be your “Default” magazine choice.

==== Mk318 Mod 0 (SOST) ==== * Visual ID: Open Tip / Lead Cliff * Best For: CQB / Short-Barreled Rifles (Mk18) Designed for “Barrier Blind” performance. It is less likely to deflect when shooting through car glass or plywood compared to the M855A1.

==== Mk262 Mod 1 (OTM) ==== * Visual ID: Black Ring / Open Tip * Best For: Marksmen / Long-Range Engagements A heavy 77-grain round that maintains its energy at distance. It does not have a steel penetrator, so it relies on raw “Stopping Power” and high damage upon impact.

Commonly found in Cold War scenarios or specialized mission crates.

The original 55-grain “Vietnam” round. It has extremely high muzzle velocity but lacks the weight or penetrator to defeat modern armor.

• Warning: Almost zero effect against Level III/IV plates.

The classic “Green Tip.” It is a Jack-of-all-trades but a master of none. In modern missions, it often requires multiple center-mass hits to down armored AI.

Black-tipped armor-piercing rounds.

• Usage: Save these for targets wearing heavy “Juggernaut” style vests or light-skinned vehicles.**

### Standard Infantry * Primary: M855A1 (EPR) * Tracer: M856A1 (Dim Trace) * Engagement: 0 - 400m ### Recon / Marksman * Primary: Mk262 Mod 1 * Tracer: None (Stealth) * Engagement: 300 - 700m

Guide Maintainer: Community Admin Last Updated: DATE Related Guides: 7.62mm NATO | 5.45mm RU