"Overpenetration" and rifle rounds--the myth that won't die

[Bartholomew Roberts]

Frangibles have unique issues of their own. From a self-defense standpoint, they are often less reliable than normal ammo. They also suffer from the same issue as anything else that won't penetrate several layers of sheetrock - they may not penetrate deeply enough in a person to stop the threat.

Maybe I'm wrong but I believe that the average CF rifle bullet does indeed pose a much greater risk of penetrating interior walls than does the average handgun round.

What ballisticians have determined is that with proper selection of .223 loads, a .223 round is less likely to present a lethal threat to a human being behind an intermediate barrier like an interior wall than a handgun round.

This is primarily because the .223 round is more likely to shed velocity and break up after passing through an intermediate barrier and the smaller fragments penetrate less. .223 is absolutely capable of killing a person through several layers of sheetrock - it is just less likely to do so than a 9mm or similar round according to FBI studies.

This is why many police departments have gone to .223 rifles instead of 9mm subguns - better terminal performance, penetrates body armor, and less likely to present a threat to bystanders.

 

[mljdeckard]

I'm not backing down on this one. 62 grain steel-core ammo is ARMOR PIERCING ammo. I cannot think of a WORSE choice to minimize over-penetration. If one were trying to deliberately over-penetrate, and hit BEHIND the target, what should they use other than this round?

Action-reaction is only one law of physics.

 

[Bartholomew Roberts]

I'm not backing down on this one.

Well, if you want to "not back down" on a factual matter that is your choice. The world will not get any flatter whether you back down or don't.

62 grain steel-core ammo is ARMOR PIERCING ammo.

First, the military issue M855 is not armor-piercing ammunition either by legal definition or practical definition. This ammunition actually penetrates LESS armor than M193 at ranges of less than 300yds (higher muzzle velocity of M193 gives it better penetration). Only at ranges of greater than 300yds does it penetrate better than M193 (better ballistic coefficient plus a tiny steel penetrator insert - not a "steel core").

I cannot think of a WORSE choice to minimize over-penetration.

The typical M855/SS109 bullet that yaws penetrates 13.4" in bare ballistics gel. Your 230gr Hydrashok penetrates 16.6".

Perhaps you would like to offer some kind of factual support for your assertions?

 

[Cosmoline]

I recall one tragic case a few years ago of a cop being killed by a 170 grain SP from a Model 94 Winchester. Not the most powerful rifle in the world yet it had no trouble defeating a vest that routinely stops .357 Magnum and .45 ACP pistol ammo.

I wouldn't suggest a 170 SP for home defense. Those are too heavy. I use lighter HP's. But I'm not sure what penetration of kevlar vests has to do with anything. The vests are designed to stop the fatter and slower handgun rounds not the thinner and faster rifle rounds. That's just the way they are. That doesn't mean the .30-30 will go through dramatically more wood after penetrating a human torso than a hard ball .45 You could build a .30-30 that would penetrate through a ton of wood. Just load it with a hardcast lead slug and it will blast through pine boards through Sunday. But the point is you have more control with the rifle round. You can make it do whatever you want it to do, within the parameters of the cartridge. Properly loaded the intermediate rifle round is ideal for defensive purposes--better at what it does than any standard handgun round and posing no greater risk of overpenetration.

 

[mljdeckard]

I don't use .45 acp for HD either.

 

[MTMilitiaman]

The 62 gr M855 is not immune to the law's of physics. It is still more likely to fragment at higher velocities. In callibrated ballistic geletin, this is typically held at around 2700 fps, below which it can not be counted on to reliably break up in tissue.

When penetrating steel, a bullet's kenetic energy turns to heat and in essence melts through armor. Velocity is squared when calculating energy, which is why higher velocity rounds like the 5.56mm in general, and the lighter 55 gr M193 in particular, are very good at penetrating steel. They concentrate a lot of energy (heat) into a relatively small point.

When penetrating barriers like wood, we often see moderate velocity rounds like the 7.62x39 do better than the 5.56, with similar bullet designs. Bullets that break up don't penetrate very well because each individual peice lacks mass, and therefore momentum, and thus sheds its velocity faster than a round that stays in one peice. And all bullets are more likely to deform or fragment at higher velocities. Rifles have the potential for higher penetration than pistols because a) most are designed for a desired effect at a given velocity. For example, a 147 gr 7.62mm M80 ball round is designed not to fragment at the standard muzzle velocity of current service rifles chambered for the cartridge. Thin the jacket out, make it more brittle, or increase the velocity, and the bullet will fragment. And b) compared to handguns, a rifle focuses a lot more energy on a lot smaller point. Thus if ammunition is choosen poorly, and not designed to break up or fragment at velocities common to your weapon and barrel length, it will penetrate farther than a handgun. But the deciding factor is bullet selection. And increasing the velocity for a given round will always, with no exceptions ever, give the bullet more of a likelihood to fragment, deform, and/or lose mass.

Take the .38 Special and the .357 Magnum, for example. With certain bullet styles, the .357 Magnum, with its relatively small frontal diameter, high velocity, and potential for long, heavy, high Sectional Density bullets, can be an excellent penetrator, at least for a handgun. But it developed its reputation on the street primarily because its velocity helped ensure that earlier JHPs expanded. These bullets often wouldn't at .38 Special velocities. JHPs expanding enlarges the frontal diameter, creating a parachute effect that slows the bullet down and reduces penetration. If you look in a loading manual, you will see many bullet companies, such as Hornady, list minimum and maximum velocity thresholds for their bullets--a minimum velocity at which the bullet can be relied on to expand in a given medium, usually ordnance geletin, and a maximum velocity it can be relied on to stick together and retain enough mass and structual integrity to penetrate.

 

[NineseveN]

I'm with ya Cosmoline, people look at me funny when I tell them what I use for HD, and it ain't a handgun. The handguns around the house are simply to allow me to get to a rifle (or even a shotgun) if need be. Handguns are a compromise that starts and ends with legality (CCW laws) and concealability. All things considered, give me a rifle with the right ammunition any time.

 

[MachIVshooter]

I'm not a ballistician or a physicist but even I know that a center-fire rifle bullet will penetrate further and deeper than handgun bullets (maybe comparing a .223 to a .454 Casull is an extreme). Note that the vests sold to cops are usually guaranteed to stop nearly all handgun ammo but as soon as a rifle is involved the warranty is voided

I used to think that too, but then I started digging deeper (and adding personal experience). Rifle rounds behave very differently from handgun rounds, period. Yes, they will invariably penetrate a hard target better (a .223 in a 24" barrel develops less energy than a .50 AE in a 6" tube, but will penetrate more than twice as much steel with standard FMJ rounds). But liquid and soft targets (organic tissues) present a very different type of barrier. Think of it this way-you jump from a 10 foot diving board and hit the water at a relatively low velocity, and you will go several feet into the water. Jump from a 200 foot off shore oil rig and you wil splatter when you hit the water at near-terminal velocity as if you had hit concrete. Perhaps not the best apples to oranges comparison, but most of us are aware of this phenomenon (that hollyweird routinely suggests won't happen).

Likewise, handgun bullets typically go 3-4 times as far in water as rifle bullets and suffer minimal deformation, while the rifle bullets tend to fragment (regardless of construction; even FMJ's do this).

When a rifle bullet enters a hard target, resistance from all sides of a material that really wants to stay together help keep the bullet in tact as it peirces, while handgun bullets lack the shape and velocity to even initiate penetration. But when fired into soft targets, the high velocity of rifle rounds can make them take very erratic paths or just plain come apart from the shock. Handgun bullets "push" through.

Bullet construction still has a lot to do with how deep x round will penetrate, but
you cannot hypothesise a rounds penetration on a living organism based on experiments with steel plate, etc.

Not being a physics major, this is about the best I can explain it. Perhaps some of our members who jumble these numbers for a living can say it better.

 

[Dr.Rob]

The BOT shows what happens with a MISS. The Federal Test shows (relatively) how much penetration AFTER miss, hitting something in between.

The old 55 grain bullet is pretty darn good all things considered for what you might want in a 'war' bullet... the abilty to shoot through stuff the bad guys are using as cover.

I understand that a lightweight 55 grain bullet at 3000 fps will shed a lot of energy if it hits something solid... but a 170gr .30 bullet designed for controlled expansion is supposed to shoot through a deer, even quartering within a 100 yards. A deer rifle is supposed to have good penetration.

If it's ALL you have, ok... but it's not the best choice.

 

[JohnKSa]

...even I know that a center-fire rifle bullet will penetrate further and deeper than handgun bullets...

You should have seen how confused the Mythbusters were when they couldn't get ANY of their rifle rounds (including a 50BMG) to out-penetrate the autopistol round they tested. (Can't remember if it was a 9mm or a .40S&W).

They were shooting into water and the rifle rounds all fragmented on impact.

Rifle rounds CAN penetrate more than pistol rounds but it's certainly not a given. As the Mythbusters test and the gel numbers prove, physics can surprise you now and then.

 

[MechAg94]

The Box of Truth found the same thing on a sand box. Rifle rounds disintegrated, but pistol rounds stayed in tact.

In water and sand, low velocity helps penetration. I am not sure that carries over to flesh.

The Box of Truth tests on dry wall only showed that .223 actually was a good performer, but the wide deflection could be a concern. Either way, you have to assume .223 will go through at least 2 or 3 full walls. I wouldn't assume any less. If so, you are not a great deal more improved over other ammunition. If you have brick exterior, you may at least feel better than most ammunition will not pass through bricks without stopping. .223 may fragment, but the fragments can still cause serious injury though they may not penetrate the next wall.

 

[SaxonPig]

Well, that's just great. Now in addition to the extensive +P testing I'm doing now I'll have line up plywood and sheets of drywall to see what will blast through them best.

Like I don't have enough to do, already...

 

[g56]

The over penetration thing is interesting, since I recently saw a video of a test paid for by DOD, and the testing pretty much confirmed the over penetration of 5.56mm ammo, penetrating a wall, then penetrating both sides of a protective vest, entering a second room and lodging in the back wall, all shown on a video for everyone to see.

When I went through firearms training at the academy we were told that birdshot in a shotgun is just about the ideal home defense round, at extremely short ranges, like inside a house, birdshot is devastating, and I've done some non scientific testing that convinced me about using birdshot, but only for extremely close range. In the last couple of weeks some of the instructors at Gunsite were being interviewed on a TV shooting show, and they said they recommend birdshot for indoor self defense, and buckshot for short range outdoor defense. This was particularly interesting to me because it confirmed the training I had received at the academy.

 

[Cosmoline]

WHAT 5.56?? It sounds like AP. Did they also have a human size chunk of bal. gel. for it to go through? Where did you see the test?

 

[Medusa]

it depends on the ammo used, and rifle. If it would be me in my crazy days I'd keep a PGM Hecate, cal .338 Lapua Magnum, 27' barrel, at hand. this one would surely shoot through a lot walls.

Otherwise 5.56 FMJ keeps the house safe, 40mm as a backup.

 

[Gewehr98]

It's settled, then.

I've shot too many living things with rifles and missed too many with handguns to have any doubts on the matter.

What have we learned? Since Cosmo can't shoot a handgun worth sour owl poop, it makes perfect sense that nobody else should use one for home defense too. I'll get right on that, I knew those nasty handguns in my nightstand were absolutely no good, even if I do well in accuracy during stuff like IPSC/IDPA/USPSA, etc.

 

[Cpl Punishment]

IF the rifle round is a non-expanding type (i.e. solid or FMJ)

AND

IF those rifle rounds hit targets that do NOT cause it to yaw and fragment, it will penetrate quite well (thus why they penetrate boards and body armor well, but fragment all to hell in fluid/semifluid mediums (like gel, bodies, etc).

IMO, this means fragmenting rifle rounds are superior in SD situation where overpenetration is a problem, so long as you hit your target. If you miss your target, no projectile (handgun, shotgun, rifle) is "safe". If you have a round that will not defeat two layers of drywall (i.e. an interior wall), I think you're crazy to trust it to stop a bad guy.

 

[Dr.Rob]

If by "birdshot" you had better mean a 3 inch #2... something like a turkey or goose load and not one meant for quail.

BOT has a lot of info on shot gun penetration, including birdshot.

 

[Cosmoline]

What have we learned? Since Cosmo can't shoot a handgun worth sour owl poop, it makes perfect sense that nobody else should use one for home defense too. I'll get right on that, I knew those nasty handguns in my nightstand were absolutely no good, even if I do well in accuracy during stuff like IPSC/IDPA/USPSA, etc.

I've put tens of thousands of handgun rounds down range through a very wide array of handguns from .22's to .454's. I wouldn't call myself a crack shot by any means but I'm a solid shot by Alaska standards. Your post highlights the limits of competition shooting. No matter how realistic it's supposed to be, it will always be artificial and it will always be set up so you can actually make the shots. After all nobody wants a competition where everybody walks away with a zero. The objective is to score points. Fun, but of limited utility. And dangerous to some extent, since it can give you a very inflated notion of your own ability and the ease with which you'll be able to nail real bad guys shooting real bullets back at you.

Real life doesn't always cooperate like that. Spending some time in the woods with your short gun trying to hit running furry things is a real eye opener. Not with a long barrel, scoped hunting handgun, mind, but the one you actually plan on using for self defense. Just go do it some time. Try to go shoot some squirrel and hare with your 1911 or whatever. See how well you do compared with a .22 rifle. If you can bullseye squirrels at 25 yards with your hand iron over and over again, you are the man now, dog ;-)

I never said handguns were "no good," I said they are purely defensive firearms of limited utility and that you should almost always choose the long gun once that option is available. For example, you might use the handgun on your night stand to guard your room's door until you can get over and get the carbine in your dresser.

 

[Bartholomew Roberts]

The over penetration thing is interesting, since I recently saw a video of a test paid for by DOD, and the testing pretty much confirmed the over penetration of 5.56mm ammo, penetrating a wall, then penetrating both sides of a protective vest, entering a second room and lodging in the back wall, all shown on a video for everyone to see.

Well, that tells us that if you shoot through drywall with 5.56 ammo of the type used in the test, you will penetrate any empty protective vests (of that particular type and construction) and still have enough energy to lodge in an interior wall. It doesn't say much about which round is less likely to present a lethal threat to an unarmored human being though. It also doesn't tell us about other alternative types of ammo that may not present the same danger.

When I went through firearms training at the academy we were told that birdshot in a shotgun is just about the ideal home defense round, at extremely short ranges, like inside a house

I had the opportunity to talk to someone who was shot in the upper right torso from 15 feet away with a load of birdshot. He made his own 911 call. He showed me the wound and it was good shot placement (or would have been had the birdshot penetrated deeply enough to reach vital organs). I would guess #7 or #8 shot; but he didn't know for sure.

 

[Richard.Howe]

Otherwise 5.56 FMJ keeps the house safe, 40mm as a backup.

Wow, that dude isn't messing around. I'd like to see what a 40mm pistol looks like.

 

[_N4Z_]

?

What academy said that? OHP? Kooky talk.

That is not such a safe thing to be preaching. Birdshot is not something to be depending on when you or yours life is on the line. Ya it'll make a big noise, it'll hurt, and make a nasty, disgusting wound, but what else? I suppose a blinding shot to the face would be good to stop a bad guy.

I'll take the 00, ahhh thank you.

 

[U.S.SFC_RET]

I hear you loud and clear Cosmoline. I understand what a pistol is and I understand what a rifle is. There is no comparison between the two. IMHO you should practically feel naked without a rifle but you have others who will always want to tell you otherwise.

 

[MTMilitiaman]

The over penetration thing is interesting, since I recently saw a video of a test paid for by DOD, and the testing pretty much confirmed the over penetration of 5.56mm ammo, penetrating a wall, then penetrating both sides of a protective vest, entering a second room and lodging in the back wall, all shown on a video for everyone to see.

I'd like to see this test, if you have the link. In order for a body armor test to mean anything, it has to have a proper backing material--usually ballistic clay--or the results really don't mean anything. The vest is only rated to withstand impact if there is something in it. And anything powerful enough to consistantly inflict lethal or dehibilitating wounds on an adult will go through several layers of drywall--including handguns.

When I went through firearms training at the academy we were told that birdshot in a shotgun is just about the ideal home defense round, at extremely short ranges, like inside a house, birdshot is devastating, and I've done some non scientific testing that convinced me about using birdshot, but only for extremely close range. In the last couple of weeks some of the instructors at Gunsite were being interviewed on a TV shooting show, and they said they recommend birdshot for indoor self defense, and buckshot for short range outdoor defense. This was particularly interesting to me because it confirmed the training I had received at the academy.

Suit yourself. I still think it is foolish. Again, I have a M870 Wingmaster with a 26 inch barrel and a turkey choke on it. My dad loads 7 1/2 shot by the hundreds since he got his Mec, so I've had a lot of experience with it on small game. I've shot literally hundreds, if not thousands of small critters. Even with the tight patterns offered by an extra full choke, it isn't uncommon to see most or all of this shot fail to penetrate a 1.5 pound ground squirrel at about 30 feet--that is about the range from my bed to the basement door. And I am supposed to rely on it to get to the vitals on a 150+ pound critter? No thanks. Just goes to show even the "experts" have to be taken with a grain of salt.

I am with Cosmoline 100%. You don't have to shoot either very much to realize that rifles are rifles and handguns are handguns. Only a fool confuses to utility and convenience of a handgun with the power, range, and accuracy of a rifle. Anyone who knows anything about what either does will choose a rifle over a handgun at the first opprotunity in all but the most extreme situations--such as a tunnel that absolutely won't allow you to use a rifle.

 

[.45Guy]

Reminds me of a quote from the novel Feast of Bones I believe. Upon arriving in Afghanistan a young Soviet VDV officer is checking in with his first unit, and is about to check a Makarov out of the armory. Luckily his crusty company CO is there with the sage advice of, "Best to get yourself a carbine, the only thing a pistol's good for here is suicide."