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05/15/2005 Archived Entry: "Range Report: Shooting concrete blocks, part deux"

SHOOTING CONCRETE BLOCKS, PART DEUX Blogispondent Ian here again. A few weeks ago, I did some experimenting on the effects various calibers had on concrete blocks. Well, that first set of blocks left me wondering about a few more types of ammo, so I made up a second set of blocks to shoot with other types of ammunition.

Once again, I used hollow 8"x8"x8" blocks which I had filled with basic Redi-Mix concrete and allowed to cure for several days. Also as before, I tested each caliber by firing a single round from 5 or 10 yards away, photographing the results, and then firing as many more rounds as seemed necessary to gain an understanding of how the ammo affected the block (and photographing the end results).

This time, the ammunition I tested consisted of .308 armor-piercing, .308 softpoint hunting ammo, .223 FMJ, .223 semi-AP, 12 gauge buckshot, and 12 gauge slugs. Here are the results by caliber:

.308 AP:
The rifle used for this was an M1 Garand with an 18" barrel. I wasn't sure how this would do, as I handloaded my .308 AP to fairly low velocity (I'm still experimenting with it and don't want to damage my rifle). The first shot knocked about a quarter of the block off and put a moderately sized hole in the core. The second shot broke the rest of the block into pieces, but left the core mostly intact. The third shot went smoothly through the core, breaking it into about a half dozen pieces. I was able to recover the steel cores from two of the three fired rounds. One was totally intact, and the other had a slight bit of deformation on the tip.

A note on .308 AP - the manufacture of AP bullets for .308 has been deemed illegal by the ATF, but this covers only the physical creation of the bullets, not the assembly of existing bullets into loaded ammo. The ATF has also ruled that surplus AP .30-06 ammo is legal for dealers to sell, unlike most calibers of AP. As a result, many dealers obtain and sell pulled bullets from surplus .30-06 to buyers who want to use them in other calibers. It happens that the bullet diameter of .30-06 is identical to that of .308 and most of the 30-caliber magnum calibers. Reloading these surplus bullets into different caliber cartridges is perfectly legal per the ATF (state laws may vary). I did just that to get my .308 AP.

.308 SP:
I used the same .308 rifle for this as the previous test; an M1 Garand with an 18" barrel. My ammo was Winchester hunting ammo, specifically 150-grain Silvertip softpoints. The first shot took literally the entire front half of the block off, as well as taking a small-to-medium sized chunk out of the core. The second shot destroyed the core and remaining block rather spectacularly, scattering pieces over a fairly large area. Its performance was very similar to the .308 FMJ I used in the first part of this experiment.

.223 FMJ:
I used a 20" Bushmaster AR-15 for this test, with 55-grain police issue FMJ ammo (I don't have a .223, so I borrowed one from a police officer I know, and he wanted to try out his duty ammo). I don't know the velocity on the stuff, but I would guess that it's comparable to commercial or military loads. anyway, the first shot was a bit low and left, and blew off a corner of the block along with a small bit of the core. The second shot removed more of the block, but didn't damage the core. The third and fourth shots hit directly on the core, and between the two of them knocked it into pieces baseball or softball sized. I found a few small pieces of lead and mangled copper jacket, but it appears that the bullets fragmented thoroughly upon hitting the concrete.

.223 semi-AP:
Here again I used the 20" AR, this time with surplus Bosnian 62-grain SS109 ammo. This ammunition has a small steel core in it, and is generally identifiable by a green tip. It's not true AP because is doesn't have a complete steel core, as as a result it is execmpted from the ATF list of banned AP cartidges. anyway, I though that this stuff would be a bit more effective than the 55gr ammo. It was, but only marginally. The first shot took off a decently-sized piece of block, but made only a small crater in the core. The second shot was low, and demolished the bottom edge of the core, while loosening another section of the block. The third shot really began to damage the core, and the fourth shot blew it apart decisively. As with the 55 grain ammo, I was able to recover only small pieces of lead and jacket material, and none of the steel penetrators. In one or two instances, it appeared to be apparent that a bullet had hit a piece of rock in the concrete core, and been deflected by it.

12 gauge buckshot:
For this caliber, I used a Winchester 1300 shotgun with an 18" barrel. The ammo was Sellier & Bellot 12-pellet 00 buckshot. I wasn't expecting a whole lot from buckshot, as its pellets are relatively soft lead, relatively low velocity, and individually fairly lightweight. The first shot made about a half dozen pockmarks reminiscent of the effect pistol ammo had on the blocks. After five shots, the entire front of the block had been removed, and the core was being worn away slowly but surely. After five shots, it had been reduced in depth no more than two inches in any place, and generally only a half-inch to inch. It would take a good number of rounds to actually break through the block, particularly if it were built into a solid wall without easily-damaged corners. No pellets were recoved, as I had expected.

12 gauge slug:
I used the same 18" Winchester 1300 for this test as the previous one. The ammo this time consisted of Federal Power-Shok rifled slugs (1 oz at 1610 fps). I was expecting these to really do a number on the block, but I ended up rather disappointed. The first shot was similar to the effect of a 55 grain .223 round - it took a small piece if the core out and knocked off two corners of the block. The second round removed a little more block and about the same amount of core. By the fourth shot all of the block had been concussed off the core, and the fifth shot finally broke the core into a couple large chunks. I suspect that the mediocre performance was the result of too much energy being used up deforming the slugs rather than demolishing the concrete. Unfortunately, I was unable to recover any slugs or even pieces of slugs, so I can't say for sure.

The same caveats apply to these tests as did to the first set I did - the results might be a bit different when the blocks were built into a complete wall. It seems to me that if the person firing on you was 50 yards away or more, a concrete block wall would be pretty good protection against most everything up to and including intermediate rifle calibers, since it would be unlikely that each shot would hit in the exact same place, thus allowing the wall to last longer.

Posted by Ian @ 01:22 PM CST

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