Hollow Points vs. Full Metal Jacket (FMJ) Ammo

Nothing will make up for shooting skill…

If you don’t hit your target it won’t matter if you were using the Golden Gun and firing depleted uranium rounds – you still missed.  But that doesn’t mean what you shoot isn’t important.

There’s an unwritten rule of firearm ammunition: use hollow points for your carry/home defense guns and use full-metal jacket (FMJ) for practice.

This is mainly due to the fact that FMJ rounds are significantly cheaper than your average hollow point.

It’s also due to the fact that, from a “put the attacker down” point of view, FMJ rounds aren’t exactly ideal.

9mm 115 gr Federal FMJ vs 124 gr Federal Hydrashok, Top
9mm 115 gr Federal FMJ vs 124 gr Federal Hydrashok, Top

That’s not to say that FMJ rounds are useless for defense.

Far from it, in fact.

Most NATO militaries use only FMJ rounds.  This is due to an international treaty that was signed many years ago that forbids the use of expanding rounds.  That same treaty also bans the dropping of grenades from hot air balloons, mind you, so some of the stuff might be outdated in the grand scheme of things.

But I digress, the FMJ is still a bullet and will still punch a hole in your average bad guy.  Stories of people “shrugging off” FMJ rounds because they “just passed right through” are rare and often exaggerated.

So why do we use hollow points then?

Ballistics Gel Testing
Ballistics Gel Testing

While a full metal jacket round will still drop a bad guy, a hollow point will do it just a little bit better.  That’s not to say there aren’t all kinds of misconceptions about hollow points as well.  What I want to do today is talk about both rounds and touch on the misconceptions of both.

Or if you’re ready…check out our Ammo & Reloading Definitive Guide for our favorite ammo picks for common calibers.

Full Metal Jacket

A full metal jacket round, as we talked about in our Basic Bullet Guide, is a soft lead bullet that’s been encased in a harder metal.

When passing through soft tissue and other stuff, the bullet retains the majority of its shape.  The upside of this is that, in theory, it has an easier time retaining its lethality after passing through a barrier among other things.  It also has an easier time working in almost any gun you put it in.

The main thing, however, is that it’s just far cheaper to manufacture FMJ ammo.

FMJ Cut
FMJ Cut

So why does FMJ ammo have that “less lethal than hollow point” thing associated with it?

It comes down to physics…

Because the bullet is just passing through, for lack of a better term, it retains a great deal of its energy.  This ultimately results in 2 small holes (entrance and exit wound) and also allows the bullet to possibly continue on for a long time and hit something you don’t want it to.

Don’t get me wrong, I don’t want 2 small holes punched in me and I don’t think anyone else does either.

It’s a safe bet that anyone, and I do mean anyone who says that a person could just shrug off a shot from an FMJ round (or a given caliber) would not be willing to stand downrange of said caliber and attempt to shrug it off.

That being said, what about the common alternative?

Hollow Points

Take an FMJ round, then drill a hole in the tip.  Hey look, the point of the bullet is now hollow.  I wonder what we could call it….Ok, it’s a bit more involved than putting a hole in a round with a drill press but still.

That hole is there to create a weakness.

Overhead Hollow Point Comparison, ar15.com Molon
Overhead Hollow Point Comparison, ar15.com Molon

 

That weakness causes resistance when it hits something squishy and that resistance causes the bullet to start expanding.  That expansion is the key point.

Remember Newton’s Law: energy cannot be created or destroyed, only transferred.  With the expansion, the majority of the energy from the shot gets dissipated into the thing what you shot.

Ideally, this results in a much larger wound cavity and no exit wounds meaning the bullet stops inside the body.  Chance being what it is, that doesn’t always happen exactly as planned but there it is.

147 Federal HST Expansion
147 Federal HST Expansion

To finish up here, I want to take a moment to explain what a hollow point isn’t.

First off, it’s not some magical death talisman.  Aside from how Hollywood likes to portray them, the person isn’t going to go flying across a room if you so much as graze their shoulder.  All it means is that this bullet is going to impact a bit harder and probably not punch all the way through someone.  If it does go through, it’s probably not going to have much power after that.

It’s also not a “cop killer” round as some like to paint it.  Even low-end body armor is far more likely to stop a hollow point than it will an FMJ round.

Finally, barriers and such aren’t going to affect hollow points as much as you would think.

First off, they need a great deal of resistance to expand which the momentary contact with a barrier just isn’t enough to cause.  Mind you, it will start to expand in most cases but they’re made to fully expand via soft tissue contact.  Secondly, most hollow point rounds made in the USA are meant to satisfy the FBI Ballistic Test requirements.

They’re pretty extensive so I’ll just give you the Reader’s Digest version: gel penetration of a minimum of 12 to 18 inches through bare gel, heavy clothing, steel, wallboard, plywood, and glass.

5 Shots into Ballistic Gel
5 Shots into Ballistic Gel

Conclusion

Like I said in the beginning…FMJ for practice and hollow points for everyday carry and such.

Does that mean you should never practice with hollow points?

Heck no!

You need to know how your gun is going to react with that ammunition.  Guns don’t always like every bit of ammo you feed it.  Put at least a box or two through your gun when practicing but, beyond that, save yourself the money at the range.

Recommendations

Previous Comments:

Posted @ 8/5/2014 5:43 PM by John

John's avatar

If the caliber designation starts with .4 it’s a moot point!

Posted @ 8/6/2014 12:04 AM by Retired lawdog

Retired lawdog's avatar

Nice Article. Good advice without pontificating.

Please help the newbies with thoughts on placement vs. speed and placement vs. ammo type. In my 35+ years “lawdoging” I’ve seen confusion on those two points.

And as far as caliber goes, the comment that “as long as it starts with .4”: Wild Bill Hickock carried a pair of 1851 colts in .36. He could have carried .44’s, but he once wrote that he used .36’s because he could aim them better and had better control for follow up shots, if needed. It’s NOT the caliber — it’s the placement of the shot(s). Many a bad guy has fallen to police round nosed bullets from a .38 special.

To all the newbies: practice with two hands, strong hand only, weak hand only and from different positions. Learn your gun and learn your capabilities — then practice to improve them. I use a pre-war Walther PPK in .32acp, and I NEVER feel under gunned.

Posted @ 8/6/2014 1:39 AM by FrankDude72

FrankDude72's avatar

Appreciate you making the distinctions for new shooters.

However, your arguments for why the hollowpoints cause more damage is not accurate.

Hollowpoints (and softpoints, and other expanding ammo) expanding create a larger diameter permanent crush cavity, thus widening the potential for incapacitating damage.

(Put more simply, bigger hole equals more likely vital bits get destroyed.)

This has very little to do with energy transfer.

(Classic example: a broadhead arrow (aka bolt) from a crossbow contains less energy upon impact than a .22 short.
Yet a broadhead arrow will cause significant more damage and thus is more likely to incapacitate its victim.)

Posted @ 10/28/2014 10:49 PM by Don C.

Don C.'s avatar

You would be correct saying the bullet expands and creates a larger diameter permanent crush cavity.

However, you are wrong in saying this has very little to do with energy transfer.

If you are talking about the force of the impact, a crossbow contains MORE energy than a .22 short. If we interchange energy and force (not technically correct, but it will work for this example) Force = Mass x Acceleration. Your arrow is going to have much, much more mass, and therefore will have more force.

As a FMJ bullet passes through a person, only a partial amount of it’s energy is transferred to the person as friction. The hollow point will transfer much more of it’s energy as friction as it’s surface area expands (as you stated correctly). It has everything to do with both energy AND expanding areas.

Posted @ 2/17/2015 7:19 PM by Ray F.

Ray F.'s avatar

I respectfully disagree. Not with the physics, Don. Not with the physics, but with the evaluation of effectiveness. Caliber debates (which essentially the same as HP vs FMJ) never end because the goal post gets shifted. One person argues killing ability, another person argues knock down power, another argues military application, etc. In civilian human on human engagement, the only goal is stopping the opponent as fast as possible. Not killing, or critically wounding, but stopping the opponent.

With proper penetration, proper placement (as has been cited) is the primary stopping characteristic. The further you get from proper placement, the bigger your projo needs to be to stop the opponent. since the energy being absorbed by the target, at best, is less than the energy being released by the shooter, the transfer of energy doesn’t have a quantifiable impact on stopping the opponent.

The only thing expansion provides is a bigger hole, which facilitates incapacitation through the more likely chance of hitting a vital or creating a quick bleed out. Unless you’re hitting brain stem and turning out the lights, the bigger the hole that is required and an exit wound helps even more. Over penetration is a civil concern…not a stopping power concern. The more leaking holes, the better, hence the ability to control/properly place and quickly follow up three head or center mass .380 FMJ rounds at 15ft has a far better chance of stopping your opponent than a single HP 10mm to the left shoulder.

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Mdnypd
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Mdnypd

As a former NYPD officer and I came across two suspects who are both shot with a 9 mm FMJ. One had three shots to the stomach area and buttocks station telling me he been shot. The second was a gentleman who shot 19 times with a 9 mm FMJ and still continue to resist with his AR 15. I’ve been shot at many a times with a 9 mm and it did not puncture my squad windshield. I can say with a high degree of certainty fmj rounds do not have any purpose for use in the field.

Viictor
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Viictor

If you want to stop a threat with your gun, you need to follow some steps, The shot placement is the first thing that have to think about. The second is tears much tissues as you can, to increase the chance to cause internal bleeding and dropping the blood pressure quickly or hit on CNS. A gun fight probably will not happend in the ideal conditions, because the threat may be on the side, with arm in front of his chest, may be behind a car door or window and wearing heavy clothes. So in my opnion, FMJ is better,… Read more »

Dan
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Dan

For every action, there is an equal and opposite reaction. The action is shooting the gun. The force of the bullet hitting the target will be equal to, or more likely, less than the recoil of the gun. There isn’t going to be as much energy being transferred to the target as people think.. Most damage will be caused by the holes made by the bullets as opposed to the force transference. HP bullets will transfer a bit more power to the target by increased friction and expanding the force of the shot over a greater diamater, but most of… Read more »

David, PPT Editor
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The rough energy is equal-ish in both directions, but the force of the bullet on the target will be far, far, FAR more than the recoil of the weapon. The energy of recoil is dampened by the mass of the gun itself, the friction coefficients of the locking system, the ergonomics of the weapon and how the force transfers to the shooter, and a few other factors. Thus how you can have firearms with only a few foot-pounds of recoil. The bullet, on the other hand, is for one thing concentrated in a smaller area, thus for the energy is… Read more »

Doug
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Doug

Damn good discussion !!

Eric Hung
Admin

Thanks Doug!

Burp Gunner
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Burp Gunner

The companies need to start making jacketed soft flat tip amminition en masse’ That would mean the Bubba Diet Root Beer crowd afford something reasonably effective in home defense, too.. Also Remington ammunition quality control has failed me twice recently. of 200 JHP 9mm Luger rounds purchased, ten were defective upon inspection. Privi Partizan, PMC, Federal, and Fiocchi donot have this problem. also. Question: is expanding metal jacket ammunition[EMJ] a good choice for defense, too?

Eric Hung
Admin

Hey Burp, I haven’t had experience with EMJ’s. What gun were you using that didn’t like the Rem ammo?

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