What Is a Hollow Point Bullet? HP, JHP, and HP BT Explained

Summary

A hollow point (HP) bullet has a hollow tip that makes it expand on impact. A jacketed hollow point (JHP) adds a copper jacket to control that expansion, and it is the defensive standard. HP BT means hollow point boat tail: the same hollow tip plus a tapered base that helps accuracy at distance.

Ammo names are full of letters: HP, JHP, HP BT, FMJ, OTM. They look like code. They are not.

Each set of letters describes the bullet’s shape and build. Once you know them, you can read any box. Here is the plain-English version.

Hollow Point vs Full Metal Jacket

A full metal jacket (FMJ) bullet has a solid, rounded nose. It holds its shape and pokes a straight hole. FMJ is cheap and reliable, so it is the standard for range practice.

A hollow point (HP) has a small pit in the nose. On impact, that pit makes the bullet open up, or “mushroom.” A wider bullet transfers more energy and stops sooner. That is why hollow points are used for defense and hunting.

What Does “Boat Tail” Add?

A boat tail is a tapered base on the back of the bullet, like the stern of a boat. It cuts drag in flight.

Less drag means the bullet stays stable and holds speed better at distance. That is why heavy, accurate loads, including most subsonic rifle rounds, use a boat tail. It is about accuracy, not expansion.

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A clear example of a jacketed hollow point defensive load:

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JHP: The Defensive Standard

A plain hollow point can deform in odd ways. A jacketed hollow point wraps the lead core in a copper jacket. The jacket controls how the bullet opens, so expansion is even and predictable.

That is why JHP is the defensive standard. Atomic’s 9mm 147gr JHP is built to expand even at subsonic speed, which many standard hollow points cannot do.

HP BT and OTM in Atomic’s Lineup

Most of Atomic’s subsonic rounds are HP BT, like the .300 Blackout 220gr. The boat tail keeps the heavy bullet accurate at low speed.

The AD77 5.56 uses a 77gr OTM, an open tip match bullet built for accuracy and duty use. Same idea, tuned for a full-power rifle load. If you know the tip and base, you can pick the right round for the job.

Frequently Asked Questions

What does HP BT mean?

HP BT means hollow point boat tail. The bullet has a hollow tip that expands on impact and a tapered base that improves accuracy at distance.

What is the difference between JHP and FMJ?

A JHP is a jacketed hollow point that expands on impact, used for defense. An FMJ is a solid full metal jacket that does not expand, used for range practice.

Are hollow points good for self-defense?

Yes. Hollow points expand to transfer energy and reduce over-penetration compared to FMJ, which is why JHP is the defensive standard.

Do hollow points expand at subsonic speed?

Only if they are designed to. Atomic’s 9mm 147gr JHP is tuned to expand at subsonic velocity, while many standard hollow points need higher speed.

What is an OTM bullet?

OTM means open tip match. It is an accuracy-first design with a small opening at the tip, used in match and duty rifle loads like the AD77.

See these bullet types in real loads. Compare the lineup below. New to ammo? Start with what is ammunition and what does grain mean.

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