5.56 ammo types explained

Why this matters

Walk into a gun store or search online for 5.56 NATO ammo and you'll see a wall of options: M193, M855, XM855, Mk262, TAP, Fusion, V-MAX, BTHP, OTM. They're all 5.56, but they behave very differently on impact. Choosing the wrong type wastes money at best and creates a safety issue at worst.

Here's what each type actually does.

M193 — 55gr FMJ (Range standard)

What it is: The original 5.56 NATO military ball round. A 55-grain full metal jacket bullet at approximately 2,950–3,050 fps from a 16" barrel (3,250 fps from the 20" military test barrel).

What it does: At close range (inside 100 yards), M193 fragments violently on impact with soft tissue when traveling above ~2,700 fps. This fragmentation is velocity-dependent — below that threshold, it pencils through like any FMJ.

When to buy it:

• Range training (cheapest option)
• Home defense on a budget from a 14.5"+ barrel (see Best 5.56 for Home Defense)
• General plinking and target shooting

Typical price: $0.28–0.40/rd

What to know: M193 is not M855. They are not interchangeable terms. M193 is 55gr, M855 is 62gr with a steel penetrator. Many new AR owners confuse them.

M855 / SS109 — 62gr FMJ with steel penetrator (Green tip)

What it is: The current NATO standard ball round. A 62-grain bullet with a steel penetrator tip under the copper jacket. Identifiable by its green-painted tip.

What it does: The steel penetrator was designed to defeat light barriers (helmets, light cover) at extended range. Against soft tissue, M855 is actually less effective than M193 — the steel tip tends to hold the bullet together rather than allowing fragmentation. It often yaws (tumbles) rather than fragments, producing inconsistent wound channels.

When to buy it:

• Barrier penetration scenarios
• If your range requires it (some outdoor ranges prefer it for backstop reasons)
• Stockpiling for general preparedness

When to avoid it:

• Home defense (poor terminal performance compared to M193 or expanding rounds)
• Indoor ranges (most ban steel-core due to backstop damage)
• Hunting (illegal in some states as "non-expanding")

Typical price: $0.30–0.45/rd

Magnetic test: Run a magnet over the bullet tip. M855 sticks; M193 doesn't. This is how ranges check.

Mk262 / 77gr OTM — Match-grade combat round

What it is: A 77-grain open tip match (OTM) bullet, most commonly loaded by Black Hills Ammunition to a military specification developed by NSWC Crane. Sierra MatchKing 77gr is the typical projectile.

What it does: Despite being an "open tip" design, Mk262 fragments reliably at moderate velocities and delivers excellent accuracy (sub-MOA from quality barrels). It was developed for SOF units who needed both precision and terminal performance from 14.5" barrels.

When to buy it:

• Precision shooting / competition
• Defensive use where accuracy and terminal performance both matter
• Duty-grade ammunition for a fighting rifle

When to consider alternatives:

• The price. Mk262-spec ammo from Black Hills runs $1.00–1.50/rd. For range training, that's prohibitive.
• Non-standard feed in some ARs. 77gr OTM can have feeding issues in rifles with tight chambers or certain magazine designs.

Typical price: $1.00–1.50/rd

Soft point (SP / JSP) — Hunting and barrier defense

What it is: A partially jacketed bullet with an exposed lead tip. On impact, the exposed lead deforms and expands, creating a larger wound channel than FMJ while penetrating deeper than frangible designs.

What it does: Controlled expansion — more predictable than fragmentation, less dependent on velocity. Soft points are the standard for hunting with .223 Remington and work well as defensive rounds through barriers.

Common loads:

• Federal Fusion 62gr — bonded soft point, designed for MSR platforms
• Hornady Soft Point 55gr — budget hunting option
• Winchester Power-Point 64gr — traditional hunting load

When to buy it:

• Hunting (where legal — check state regulations on caliber minimums for deer)
• Home defense in short-barreled rifles where M193 won't reach fragmentation velocity
• Duty/barrier use where bonded expansion is preferred over fragmentation

Typical price: $0.55–1.00/rd

Polymer tip — Varmint and defense

What it is: A hollow point filled with a polymer tip that initiates expansion on impact. The tip also improves aerodynamics for better long-range accuracy.

Common loads:

• Hornady V-MAX 55gr — aggressive expansion, varmint and light defense
• Hornady TAP / Frontier HP — V-MAX equivalent marketed for defense
• Nosler Ballistic Tip 55gr — similar design, hunting-oriented

What it does: Explosive expansion at all velocities. Polymer tips are less velocity-dependent than M193 fragmentation, which makes them better choices for short barrels. The tradeoff is sometimes shallow penetration — they can break apart before reaching adequate depth in heavy-set individuals.

When to buy it:

• Varmint hunting (coyote, prairie dog)
• Home defense from short barrels (see Best 5.56 for Home Defense)
• Where maximum expansion and reduced over-penetration are priorities

Typical price: $0.50–0.85/rd

Quick comparison table

What to buy (simplified)

Range training: M193 55gr FMJ — cheapest, universally available, runs in everything.

Home defense (16" barrel): M193 works. Hornady V-MAX or Federal Fusion if you want purpose-built.

Home defense (under 12" barrel): Skip M193. Go polymer tip or bonded soft point.

Hunting: Soft point or polymer tip, 55–62gr depending on game size. Check state caliber/bullet-type regulations.

Precision / competition: 77gr OTM (Mk262 spec or equivalent) for the best accuracy and terminal performance.

Compare 5.56 NATO prices across retailers → | Check current CPR on the Price Index →

Related articles

• .223 vs 5.56
• Best 5.56 for home defense
• FMJ vs hollow point

Sources

• 5.56×45mm NATO — Wikipedia — M193, M855, and Mk 262 specifications
• SAAMI Cartridge Standards — Pressure specifications
• Hornady Frontier Product Line — Manufacturer specifications