Agreeing and expanding on feedback from Gzire.  There is a pretty big difference between brick (mostly unreinforced) and CMU and grouted CMU (cells filled with grout, which is basically the same as concrete for the purpose of this topic).  I would have to check, but I believe fully grouted CMU meets the requirements for structures requiring ballistic protection.    I am not sure if ungrouted CMU qualified.  In the case of ungrouted CMU, most times only certain cells are filled with grout. 

In any case, I would doubt that most homes have ALL of the interior partitions that are constructed out of fully grouted CMU.  Some of the load bearing walls might, but that is usually not required or cost effective for single family residences.  For highrises, the vast majority of interior partitions are drywall/gyp board.  Those pretty much do nothing against most rifle and pistol rounds, even when doubled up for sound attenuation. 

The typical CMU construction locally consists of the main blocks with a minimum compressive strength of about 1500 psi with grout with a minimum strength of 2000 psi.  When constructed and tested, the combined assembly will often test out to beyond 3000 psi compressive strength, which would equivalent to most basic concrete walls.  Just something to consider.  However, that is from a strength of materials perspective and not ballistics. 

I would love to see how an M4 does against a shotgun with 00 buck though.  I would think that both would damage the surface of the CMU, but nothing beyond an inch or so. 

This is becoming a very interesting thread...

Found this on Youtube.

US Marines Ammo penetration tests on Youtube.


Tested material were against sheet rock, plywood, cinder block and bricks.  Angles at 0 and 45 degrees.   Tested weapons were AK47, M16, M249 SAW, M40A1 sniper rifle, M240G MG, M2HB 50 and M82.


VeryLowBudget also has a bunch of penetration tests against a wall and an old refrigerator.
http://www.youtube.com/user/VeryLowBudget

1. 9mm vs wall and fridge


2. M4 vs wall and fridge


3. 12 ga slug vs wall and fridge


4. 12 ga buckshot vs wall vs fridge


5. M4 223 vs Cinderblocks and wall


A few more videos on his channel including bullets against his old car.

I have a solution that will fix all the potential problems of the topic.

















  Don't miss 

....would put holes through my brick walls and possibly hit my family member.

My question is this. Do you know for sure that the wall(s) between your bedroom and your family's rooms are CMU? My guess would be drywall and stud. Do you know?

This is becoming a very interesting thread...

Found this on Youtube.

US Marines Ammo penetration tests on Youtube.

Tested material were against sheet rock, plywood, cinder block and bricks.  Angles at 0 and 45 degrees.   Tested weapons were AK47, M16, M249 SAW, M40A1 sniper rifle, M240G MG, M2HB

Wow, so a ballistics EXPERT and the United States Marines Corps both agree that .223 rounds penetrate walls.

Interesting. Maybe Buckjay should call them and tell them that they're mistaken.

He can show him his hand drawn graph to refute their tests. That'll sway em.   

My question is this. Do you know for sure that the wall(s) between your bedroom and your family's rooms are CMU? My guess would be drywall and stud. Do you know?

Cinder block, not brick...  My apologies.  I thought they were the same, but it's definately cinder block.  I tried to hang my flatscreen on my wall but thats when I learned all my interior walls are cinder block as well. 

Cinder block, not brick...  My apologies.  I thought they were the same, but it's definately cinder block.  I tried to hang my flatscreen on my wall but thats when I learned all my interior walls are cinder block as well.

Cinder block is another way of saying CMU or Cement Masonry Unit. Here in Hawaii the common term for CMU is Hollow Tile. Anyway, if you are really and truly concerned the next step would be to find out if the CMU is hollow or solid grouted. The easiest way to find out would be to use a small masonry drill and if you continue to drill into hard material in say 4"-6" I would say it is solid grouted. I know this is not an optimal method as it is slightly destructive. But it is important to know. Because a hollow CMU will probably NOT stop a .223. But a solid grouted CMU probably WILL stop a .223. And this is the answer to your question is it not?

WTF!!  I would not bullshit about this kind of stuff on here, and i swear on my family's, and my own life... I  Was taking a sh*t, and i can hear my neighbors (guy and girl) yelling at each other and just going at it.  It sounded like he was beating somebody up and yelling, and i could hear the female screaming to stop.  Then all i hear is BOOM!!!  sounded like a shotgun or a big caliber firearm.  Then all i hear is, "i going fuken kill you, i going fuken kill you!"  i ran out of my bathroom and my girls parents were thinking it was a firecracker.  Until they saw me run into my bedroom and bring out my M4.  My adrenalin was pumping boy!!  I swear to god the first thing i thought about was 12 gauge or M4!!  This is so ironic, i am going to save this thread and show my friends and family that i'm not being paranoid!  They were yelling at each other for a few minutes, but nobody wanted to call the cops in my house, because you can easily hear us talking on the phone next door, and we didn't want any trouble.  My girls mom went in her room to call the cops, but she ended up coming out and saying she was scared, and somebody else will call.  It's been about 20 minutes since the BOOM, and still no police next door!  There was one point where it sounded like the female was crying for her life, like he was pointing a weapon at her, then i heard their baby start screaming and crying.  I was just waiting for another BOOM!  But i was praying i wouldn't.  I am about to leave my house right now and go to the wahiawa police station, but i'm tripping out about this right now, and i had to write about this while it's still fresh...  F*ck man, this is like the 3rd time i heard gun shots from that house and only seen police there once.  This is the kind of sh*t i need to live with, and now you can kind of see why i am the way i am...  I just hope he's one of those guys that will just shot off rounds in the air, and not at family... 

And it's confirmed that it was a gun, because my girl could hear the female screaming about putting the gun away, and i could hear the guy threatening to kill somebody... 

*I'll update you what happens after i get back from police station...  *anybody else here from wahiawa?? anybody heard the shot??

holy shit man! i hope someone called the cops

no other 911 calls about this! didn't make an official report.  I don't think i should have wrote what i did publicly on here for my safety, but i want people to know that this thread actually was worth something...  it made me feel comfortable that we discussed about potential projectile penetration of my type of building construction, and i felt like i was prepared and knew what to expect if rounds came towards my walls.  i took some pictures of the doorway and window of my home to see if you can tell what kind of construction it is...  it looks like it's cinder block filled with something. 

I think you're pretty much good to go with that.  You're not going to find sturdier walls outside of Mexico or (I'm told) the Phillipines.  My ex father-in-law's house in Mexico had no shit 12" of poured concrete for INTERIOR walls, and all the exterior walls were at least 18" thick.  And for the love of God, keep your rifle close at hand!  You've got some crazy-ass neighbors!

I think you're pretty much good to go with that.  You're not going to find sturdier walls outside of Mexico or (I'm told) the Phillipines.  My ex father-in-law's house in Mexico had no shit 12" of poured concrete for INTERIOR walls, and all the exterior walls were at least 18" thick.  And for the love of God, keep your rifle close at hand!  You've got some crazy-ass neighbors!

18" thick??  wow...  the only thing i would be worried about in a fortress like that is earthquakes.  But i'd feel safe as hell in there.  So far my neighbors keep to themselves, and never give me any problems when i drive by or when i'm yelling and fighting with my GF at home..  nearly every weekend i can hear fighting, and yelling, but they never bothered me.  I always end up living in f*cked up places for some reason, but always find out months after.  I lived in the plantation housing in waialua (Mill Camp) for about 7 years, and i could hear my samoan neighbors shooting their guns all the time, but they were a cool family and never started trouble with anybody around our area.  And i shit u not, there were multiple fights around my house in waialua every month, and i've seen knives, spear guns, pellet guns, bats, u name it, they fought with it down there.  I even have a video with 2 chronics fighting outside my house: one with a spear gun, and the other guy was just throwing big ass rocks at him from a distance. what's going on now days? 

no other 911 calls about this! didn't make an official report.  I don't think i should have wrote what i did publicly on here for my safety, but i want people to know that this thread actually was worth something...  it made me feel comfortable that we discussed about potential projectile penetration of my type of building construction, and i felt like i was prepared and knew what to expect if rounds came towards my walls.  i took some pictures of the doorway and window of my home to see if you can tell what kind of construction it is...  it looks like it's cinder block filled with something. 

While you might feel safer from your neighbor I would still stay away from the windows when they are arguing.

So now that we know your walls are solidly grouted your walls are pretty much bullet proof with the exception of maybe a 50 cal or 20mm. But now you have another problem. That problem is with ricochets. You fire off that 223 inside your house you have a chance of getting hit with your own round. And anyone within the range of your ricochet has a chance of getting hit. Under the circumstances I would say that a shotgun is probably the best SD gun for your particular circumstances. The reasoning is that 00 shot will lose energy quicker (due to lighter weight per projectile) when it strikes your walls. This will limit the amount of ricochets and the power they have to do damage to someone after they ricochet. In your particular case good aim is probably the best defense with a lesser chance of collateral damage.

Hopefully, this will help you in making your decision in what firearm to use for self defense.

Twin - In the first of the two photos that you posted, was that opening cut into that wall for the door (at least it looks like it was a door)?  Or was it constructed like that? 

The reason why I ask is that for typical headers (the horizontal section of the wall over the door) it is usually easier to build that section with a different block where the bottom is solid, like the side walls of the typical units.  However, that is what I've seen mostly commercial construction and I haven't done single family residences in Hawaii in a long time. 

Anyways, the areas around the openings are typically grouted since they are reinforced (have steel reinforcing bars in the cells) around the openings.  You may very well have solidly grouted walls, but I can't tell from the pictures.  Sometimes you can tell if you have any electrical outlets or switched embedded in the wall.  It is usually pretty easy to tell by looking if there are voids behind the outlet box.  Another way to test that doesn't require drilling is to sound the wall with a hammer.  But the difference in sound from solid grout to partially grouted (where only the cells with reinforcing, usually at around 24", 32", 48" spacing).

Yeah, what's up with all this craziness?  I guess bad economy putting pressures on everyone.  Be careful and definitely stay away from your windows when the neighbors start going nuts! 

Twin;
1.  I'm glad no one is hurt
2. You need to move.
3. The cells look to be grouted in the CMU, but that's rather common around openings.
4. Sometimes the engineer may call for grouting every other cell.  Inspector's got a good idea about drilling into the wall to see if all the cells are grouted.

you should be able to tap on it with a hammer in different spots to hear if it's hollow or not

I am no expert but if you want to use the shotgun you could always go for a reduced power load. The tactical loads come out of the barrel a little slower than the regular loads. So if you find a load with a lower FPS rating then penetration will be less.  I think a hollow tile wall filled with concrete would stop most rounds. If they are left unfilled then not so sure.

Ideally a pistol is probably better for home defense. I do believe 00 buck has always been considered a good self defense round though. You might be able to find a manufacturer making a round specifically to prevent over penetration.


One might consider the stance when firing. If you are in a single story home you could squat so that a torso shot would continue upwards above anyone else head if it over penetrated.

I am no expert but if you want to use the shotgun you could always go for a reduced power load. The tactical loads come out of the barrel a little slower than the regular loads. So if you find a load with a lower FPS rating then penetration will be less.  I think a hollow tile wall filled with concrete would stop most rounds. If they are left unfilled then not so sure.

Ideally a pistol is probably better for home defense. I do believe 00 buck has always been considered a good self defense round though. You might be able to find a manufacturer making a round specifically to prevent over penetration.


One might consider the stance when firing. If you are in a single story home you could squat so that a torso shot would continue upwards above anyone else head if it over penetrated.

I always think about my stance LOL..  i always think if i should stand on my bed and shoot downwards, or crouch down/ lay down and shoot upwards...  standing on the bed is just asking for it, so i'm always considering crouching on the ground.  I have landlords that live upstairs, but i don't think they'll mind stray bullets flying upwards near their feet.

Project Metropolis huh? Looks an awful lot like an American-stylle mock city they are practicing on.

From a well made AR manufacturer (cough cough):  http://www.olyarms.com/index.php?option=com_content&task=view&id=15&Itemid=26 first article that talks about penetration though in my mind not enough data to properly extrapolate anything.  Twist rate of the AR barrel, etc.  Any round will penetrate a simple stud drywall though what happens after is what counts.  From what extrapolating that data it seems that the heavier rounds have more penetration vice the lighter rounds fragmenting faster.  Either way in a concrete structure thats alot of lead bouncing around and putting up drywall, bookcases would help in minimizing ricochets unless those ricochets are all headed towards the bad guy.

Gulf seafood??