What Is the Difference Between Hollow Point and FMJ Ammo?
Full metal jacket (FMJ) ammunition has a solid copper jacket that covers the lead core, causing it to retain its shape on impact and penetrate deeply. Hollow point (HP) ammunition has an open cavity in the nose that causes the bullet to expand on impact, creating a larger wound channel while reducing over-penetration. FMJ is for training and range use. Hollow points are for self-defense and hunting.
Why It Matters
Choosing between FMJ and hollow point is one of the most important ammunition decisions. FMJ rounds can punch through multiple walls and continue with lethal energy, making them dangerous in defensive situations where over-penetration threatens bystanders. Hollow points are designed to expand and stop inside the target, transferring energy more efficiently and reducing collateral risk. Using the right type for the right purpose is both a safety and effectiveness issue.
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Full Metal Jacket (FMJ):
- Copper jacket fully encases the lead core (except the base)
- Retains shape on impact — does not expand
- Penetrates deeply, often 24 to 36 inches in ballistic gelatin
- Feeds reliably in all semi-automatic firearms
- Less expensive ($0.25 to $0.50 per round for common calibers)
- Used for: range practice, training, competition, military use (required by Hague Convention)
Hollow Point (HP):
- Open cavity in the bullet nose causes controlled expansion on impact
- Expands to 1.5 to 2 times original diameter
- Penetration typically 12 to 18 inches in gelatin (FBI standard)
- Creates a larger permanent wound cavity
- More expensive ($0.75 to $2.00 per round)
- Used for: self-defense, concealed carry, home defense, duty use, hunting
Other common types:
- Soft Point (SP): exposed lead nose, partial expansion, good for hunting
- Bonded: jacket chemically bonded to core, maintains weight through barriers
- Open Tip Match (OTM): small opening for manufacturing accuracy, not designed to expand
- Frangible: compressed powder metal, breaks apart on hard surfaces, used for steel target training and close-quarters
FBI penetration standard: 12 to 18 inches in calibrated ballistic gelatin. Less than 12 inches risks failing to reach vital organs. More than 18 inches risks exiting the target and hitting bystanders.
Build Impact
Most modern semi-automatic pistols and rifles feed hollow points reliably. Older 1911s and some budget firearms may have feed ramp issues with hollow points — test any carry or defensive firearm with your chosen hollow point ammunition (at least 200 rounds without malfunction) before trusting it for self-defense. Some states restrict hollow point ammunition — check your state and local laws.