5.56 NATO vs .223 Remington: 2026 Comparison
5.56 NATO chamber wins for flexibility. A rifle chambered in 5.56 NATO can safely fire both 5.56 NATO and .223 Rem ammunition. A .223 Rem chamber should only fire .223 Rem due to the higher operating pressure of 5.56 NATO loads. For most AR-15 buyers, a 5.56 NATO (or .223 Wylde) chamber offers maximum flexibility. Ballistically, the rounds are nearly identical; pressure ratings and chamber specs are the key distinction.
| SPEC | 5.56 NATO | .223 REMINGTON |
|---|---|---|
| Bullet Diameter | .224" | .224" |
| Case Length | 45mm | 45mm |
| Max Pressure (SAAMI/NATO) | 62,366 psi (NATO) | 55,000 psi (SAAMI) |
| Typical Grain Weight | 55–77gr | 55–77gr |
| Avg Cost/Round | $0.30–$0.45 | $0.28–$0.42 |
| Chamber Compatibility | Fires both 5.56 & .223 | .223 ONLY (safe) |
- + Safe to fire in .223 chamber rifles? No — but the reverse is true
- + Higher velocity possible with heavier loads
- + Military surplus availability
- + Wider retailer selection for bulk ammo
- − Unsafe to fire in .223-only chambers
- − Slightly higher pressure can affect accuracy in some .223 chambers
- + Slightly lower pressure = gentle on barrels
- + Wide availability of match-grade loads
- + Typically marginally cheaper
- + Safe to use in .223 Wylde and 5.56 chambers
- − Cannot safely fire 5.56 NATO loads
- − Less mil-surplus availability
- − Limiting chamber choice for flexible shooters
A rifle chambered in 5.56 NATO can safely fire both 5.56 NATO and .223 Rem ammunition. A .223 Rem chamber should only fire .223 Rem due to the higher operating pressure of 5.56 NATO loads. For most AR-15 buyers, a 5.56 NATO (or .223 Wylde) chamber offers maximum flexibility. Ballistically, the rounds are nearly identical; pressure ratings and chamber specs are the key distinction.