Hollow Point (JHP) Bullets Explained — Self-Defense Ammo Guide

Hollow Point (JHP)

A hollow point bullet — usually called JHP for 'Jacketed Hollow Point' — is a projectile with a cavity machined into the front of the bullet that causes the bullet to expand on impact. The expansion increases the bullet's diameter, transferring more energy to the target and reducing the risk of over-penetration through walls or bystanders. JHP is the standard design for self-defense and law-enforcement ammunition. FMJ (full metal jacket) is the standard for training and military use.

How a hollow point actually works

A hollow point bullet is identical to an FMJ at the rear — same caliber, same case head, same primer, same powder charge. The difference is the nose:

The lead core has a cavity (the "hollow point") machined into the front.
The copper jacket has "petals" — pre-cut score lines that encourage the jacket to peel back symmetrically on impact.
When the bullet hits soft tissue (or gelatin in testing), the cavity fills with fluid. Hydrodynamic pressure forces the jacket petals outward, increasing the bullet's diameter typically from 0.355″ (9mm) to 0.55-0.65″ — a 50-80% increase in frontal area.
The expanded bullet transfers more energy per inch of penetration, and the larger frontal area decelerates faster — both reducing over-penetration risk.

The FBI ammunition spec — why it matters

The FBI's 1989 ammunition tests (post-Miami shootout) established the modern self-defense ammunition standard:

12-18 inches of penetration in calibrated 10% ordnance gelatin, AND reliable expansion to at least 1.5× the original bullet diameter, through multiple barrier types (heavy clothing, plywood, drywall, sheet steel, auto glass).

Modern duty JHPs are designed against this spec. The 12-18 inch penetration range matters because:

<12 inches: Bullet doesn't reach vital structures through arms, heavy clothing, or angled torso shots.
>18 inches: Bullet over-penetrates, risks bystander injury through walls.

Several "light + fast" JHP designs (Liberty Civil Defense, Pow'R Ball, RIP) deliberately fail the FBI spec by under-penetrating in exchange for explosive expansion. These are gimmick designs that instructors generally advise against.

The duty-grade short list

Federal HST — the dominant self-defense JHP. Used by NYPD, LAPD, and many federal agencies. 124gr +P or 147gr 9mm are the benchmark loads.
Speer Gold Dot G2 — current FBI duty round. Bonded jacket prevents jacket separation on barrier shots.
Hornady Critical Duty FlexLock — designed specifically for barrier penetration (auto glass, drywall). 135gr or 147gr 9mm.
Winchester Ranger T (RA9T) — the FBI's former duty round; widely-available now under the Ranger label.
Sig V-Crown — newer entry, performing well in independent gelatin testing.

Common myths to ignore

"Hollow points are illegal under the Geneva Convention." The Hague Convention of 1899 (NOT Geneva) prohibits expanding bullets in international armed conflict between signatory states. That treaty has no application to civilian self-defense, law enforcement, or domestic conflict. Civilian use of JHP is legal in 49 US states.
"A hollow point can't penetrate through clothing." Modern duty JHPs are explicitly designed to expand through heavy clothing (denim, leather, multiple t-shirts). The FBI gel test includes a four-layer denim barrier.
"Bigger expansion = better." Past about 0.65″ diameter, additional expansion comes at the cost of penetration. The FBI 12-18" spec is the meaningful metric.
"Use FMJ because hollow points won't feed." Untrue for modern carry guns. Test your specific gun + ammo combination; modern JHP designs feed reliably in everything from a P365 to a 1911.

Frequently asked

Are hollow points illegal?

For civilian self-defense in the US, no — hollow points are legal in 49 states (New Jersey has historical restrictions that have been narrowed). They're the recommended self-defense round by virtually every firearms instructor. The 'illegal' confusion comes from the Hague Convention of 1899 (often misremembered as the Geneva Convention) prohibiting expanding bullets in INTERNATIONAL ARMED CONFLICT — that's a treaty between countries fighting wars, not a law applying to civilian self-defense or domestic law enforcement.

Why do police use hollow points?

Two reasons. First, expansion improves terminal effectiveness so officers can stop a threat faster. Second, hollow points reduce over-penetration — they're designed to expand and slow down inside the target rather than passing through a wall into a bystander. The FBI requires 12-18 inches of penetration in gelatin tests AND expansion to ~1.5x original diameter; modern duty JHPs (Federal HST, Speer Gold Dot, Hornady Critical Duty) all meet those criteria.

What's the difference between JHP and FMJ?

JHP (Jacketed Hollow Point) has a cavity in the nose that causes expansion on impact. FMJ (Full Metal Jacket) has the bullet's lead core completely encased in copper jacket with a closed, round nose — it does NOT expand. FMJ is cheaper to manufacture, feeds reliably in most pistols, and is the standard for range training. JHP is more expensive, sometimes finicky in feeding (modern designs solve this), and is for self-defense use. See our 'FMJ vs JHP' page for the deep comparison.

What's the best hollow point for self-defense?

By FBI gelatin test data, the leaders are Federal HST (152gr 9mm tested at 12.5" penetration, .61" expansion), Speer Gold Dot G2 (recent FBI duty round), Hornady Critical Duty FlexLock (147gr designed for barriers), and Winchester Ranger T. All meet the FBI 12-18" penetration spec and expand reliably. Avoid 'gimmick' ammo (Liberty Civil Defense, RIP, etc.) that prioritizes velocity over the proven penetration + expansion combination.

How much does hollow point ammo cost?

About $0.80-$1.50 per round for quality 9mm self-defense JHP, vs $0.25-$0.40 for 9mm FMJ training ammo. A 20-round box of Federal HST runs $24-32. The cost premium is why most defensive shooters train with FMJ and carry JHP. Recommended cadence: shoot 50-100 rounds of your carry JHP per year (to confirm it cycles in your specific gun) and use FMJ for everything else.

Do hollow points feed reliably in every gun?

Modern carry guns (Glock 19, Sig P365, S&W Shield Plus, Sig P320) are designed to feed JHP reliably and almost always do. Some older pistols (1911 with un-modified feed ramp, older S&W Sigma, certain compact pistols with tight chambers) can have issues with hollow-point nose shapes that are wider than FMJ. The fix is to test 50-100 rounds of your specific JHP through your specific gun BEFORE carrying it. If it doesn't cycle reliably, try a different brand or have a gunsmith polish the feed ramp.