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03/27/2005 Archived Entry: "Range Report: Shooting concrete blocks"
RANGE REPORT: SHOOTING CONCRETE BLOCK
If someone starts shooting at you, what can you safely hide behind? Blogispondent Ian here again. It's a question I've seen a lot of speculation on, and only a little bit of actual, reproducible testing. So, I decided to grab some guns and targets are work on finding out for sure. Specifically, I decided to test concrete block walls.
I'm sure you've seen the concrete blocks that are 8" by 8" by 16", with two hollow cores. For my test, I bought a half dozen of the 8" cubic single-core blocks, and also a bag of basic redi-mix concrete. I mixed up the concrete, filled the cores, and let them cure for 72 hours (which should be plenty of time for the small amount of concrete in each block to come to full strength). Here's the finished product, ready for shooting. Note: be aware that the photos linked to here are fairly large, ranging from 200k to 500k.
On the other end of the testing, I chose six guns of common but varied calibers: a .22 rifle, a snub-nosed .357 Magnum revolver, a 9mm automatic, a .45 automatic, a 7.62x39 rifle, and a .308 rifle. I plan to repeat the test at some point with some other common rounds (.223, 12ga, etc).
Doing the testing was as simple as setting the blocks on the ground, stepping back a few yards, and shooting them up. For each caliber I fired one shot, inspected the results, and then fired as many more shots as seemed necessary to judge effectiveness. Here are the results by caliber:
The gun used for this was a Henry lever-action rifle. Ammo was Remington Golden Bullet high-velocity hollow points. The shooting was done from 5 yards. The first round, as expected, made a small crater in the block (roughly nickle-sized and a quarter-inch deep). It took 14 more rounds in the same spot to dig a hole through the block down to the concrete core. I wasn't sure how the strength of the core compared to the block, so I next turned the block on its side and fired 5 rounds at the exposed top of the core. They made a decent hole, and it appears that the .22s have about the same effect on the block and core. I was unable to find any fired bullets from the .22.
The gun used for this was a Ruger P94. Ammo was American Eagle 115gr FMJ. Shooting was done at 5 and 10 yards. The first series of shots were at 5 yards, and the initial shot was impressive. It hit a bit low on the block, made a crater over an inch in diameter and almost as deep, and broke a piece of block off. Seven more rounds proceeded to break up much of the front o the block. However, I was being noticing some ricochets, and so I moved back to 10 yards for the second group of shots. At that distance, another 7 rounds served to break more than halfway through the core. I did recover several bullets from this test (including one that bounced off my leg). They had expanded to around 15mm - the tip of the jackets were demolished, though the bullets remained in one piece and formed a classic mushroom shape.
The gun used for this was a S&W Model 60 revolver with a 2" barrel. The shooting was done from 5 yards. I couldn't find any .357 FMJ, so instead I fired one .357 Mag hollowpoint, and followed it up with some .38+P fully jacketed flat points. The first round, the magnum, was surprisingly ineffective. It made a crater slightly smaller than the 9mm. This may have been because it was a hollowpoint and more of the impact energy went into deforming the bullet, or possibly because the 9mm bullet was pointed, concentrating the energy from its impact. In any case, five subsequent rounds of .38+P did little more, making small craters but leaving the block structurally intact. I was able to recover the .357 Mag bullet (though none of the .38s). It had completely shed its jacket, and flattened almost completely into a disc. Its end diameter was right at a full inch.
.45 ACP: The gun used for this was a government model 1911. Ammo was Wolf 230gr FMJ. Shooting was done from 5 yards. Again, the effect of the first round fired was disappointing. It left a crater even smaller than the .357 Mag (though largter than the .22). However, after six more rounds roughly a third of the block had been broken up and the core had been damaged slightly. I recovered several of the bullets, and they had all mushroomed out to about 3/4 of an inch in diameter while remaining in a single piece.
7.62x39mm: The gun used for this was a Romanian AK-47, with a 16" barrel. Ammo was Silver Bear 123gr FMJ. The shooting was done from 10 yards. The first shot knocked a corner of the block off. Four more shots were required to satisfactorily demolish the rest of the block and its core. The bullets I was able to recover were reduced to mangled partial cores and jackets. Steel-cored ammo would probably be more effective, since its cores would deform a good deal less.
.308 Winchester: The gun used for this was an M1 Garand with an 18" barrel. Ammo was surplus Indian 147gr FMJ (yes, it is crappy ammo - I had one clip left and wanted to be rid of it). The shooting was done from 10 yards. The first shot blew the front side of the cement block into several pieces, knocked it thoroughly off the cement core, and did some slight damage to the core. A second shot handily demolished the core of the block and knocked the remaining block sides into several pieces. Recovered bullets were indistiguishable from those of the AK, and again steel-cored ammo would probably be even more effective.
Overall, it seems to me that a concrete block wall would be pretty good cover against all but the heaviest calibers in a gunfight. All the pistol calibers would take quite a few rounds to break through, particularly if they didn't all hit in nearly the same spot. Even the 7.62x39 took enough that if one was firing on you, you would have time to move a few feet one way or another before a section of the wall was gone. However, the .308 would take only two or three rounds to make a legitimate hole in the wall and put a round into whatever was behind it.
Keep in mind that this all assumes that every core in the wall has been filled with concrete - which is rarely the case (it will be done in any wall I build, though). If you're hiding behind a hollow-core wall, all bets are off. My guess is that you would be basically impervious to .22 and light pistols, have a few rounds' protection from heavier (9mm and up) pistol fire, maybe one round worth of protection from assault rifles, and only concealment from the heavy rifle calibers. Also, my test didn't take into account the fact that a block wall would be stronger than individual blocks. I didn't want to take the time or money to build six complete sections of wall, and I think that the results I got with individual blocks are quite close to what you would see with a whole wall.
As I said in the beginning, I plan to repeat this experiment using other common calibers in the future. I will try out shotgun slugs, buckshot, .223 (if I can get my hands on a .223 rifle), and AP .308 or .30-06. Hopefully I can also get the chance to test some other types of cover (if you have any in mind that you are particularly interested please let me know - send me a PM on the forum or an email through the webmistress here).
Posted by Ian @ 03:03 PM CST