This is a subject that appears from time to time, and it was raised again recently.
The question is whether frangible bullets are safe to fire toward other people in adjoining rooms because of the assumption that they will break up into harmless pieces when they strike building materials. I have long believed that because they had to resist the shock of being chambered and fired, breaking up by striking wood and wall board was unlikely at best. I had, however, never tested my belief myself. Now I have.

The following test was of course not as comprehensive as it could have been. I tested only two types of ammunition and against only one type of building material. But it did demonstrate that a certain building material (2×4 wood boards) did not eliminate the danger of passthrough by two types of bullets.

The test used Speer 357 SIG ammunition loaded with 100 grain bullets and remanufactured Ultramax 223 Remington ammunition loaded with 42 grain bullets. Both bullets appear to be made of copper powder and are intended to break up into tiny, less-dangerous fragments when they strike hard targets. I attempted to measure the velocities of the two loads, but without success, and probably because the targets were too close to the LabRadar unit.

The first two shots were fired through two 2×4 boards clamped together. When it became obvious that two boards offered no significant resistance to the handgun load, I went to using a single board. I used manila folder tagboard for witness behind the board and one gallon jugs filled with water behind the paper. Both rifle and pistol ammunition were fired at close range; about 3 yards for the pistol and about 10 yards for the rifle. Barrel lengths were 3.9 and 16 inches respectively (SIG P229 and carbine length AR).

The setup:




The first two exit holes through two boards:



The first shot veered off so far that it didn’t even hit the witness paper. The second shot hit high and right while tumbling. The third shot also missed the water jugs, but finally the fourth shot hit a jug.

Handgun entrance holes.




Witness paper after four shots, three of which hit the paper.



Handgun exit holes:



Water jug hit by handgun bullet:



Upper rim of plastic barrel struck by handgun bullet.




Loaded cartridge and broken bullet recovered after striking barrel clamp.



Entrance and exit holes from 223 ammunition.





Witness paper showing 223 bullet hits. The circled hole below the brown square paster was a sighter shot. The upper right two holes were evidently made by the bullet that broke in two. That shot struck the water jug.




Water jug struck by 223 bullet.



The last photo shows the imprecision and inaccuracy of the Ultramax load. The three holes at the lower right, one in the manila paper and two in the cardboard were fired from a hasty rest from about 27 yards. The three holes below the brown paster were fired from the same rest with Lake City M193 ammunition. Although a better rest and using a larger, easier to see aiming point would have probably resulted in a much smaller group, that’s about what I expect with that rifle and ammunition. (Four shots were fired for the group; the upper right hole was made by two bullets.) I regularly score the equivalent of head shot hits at 25 yards with bulk M193 ammunition and Aimpoint sight, but I wouldn’t try that with the Ultramax frangible.




In summary, both the handgun and rifle frangible bullets easily perforated the 2×4 board. All bullets tumbled after exiting the board, as would be expected of most projectiles. With possibly one exception, they did not break up as a result of passing through the board. They tended to veer off the original line of flight. The bullets that struck the water containers did cause significant damage. None of the damage seen in this test can be converted directly to wound ballistics information except for the fact that it’s obvious the bullets could have caused serious injury if they had struck a person.

This message has been edited. Last edited by: sigfreund,

Modern frangible ammo serves one purpose: to minimize ricochets and frag from hard surfaces (metal, brick, concrete, etc.) during training. It's used as a training aid, to allow folks to more safely train in close quarter shoothouses and with close-range steel targets. (Otherwise, you're looking at minimum safe distances of like 15 yards for handguns and 50-100 yards for rifles, with normal FMJ on steel targets.)

As you noted, it is not designed to prevent penetration through drywall or other similar building materials. That is an internet fallacy.

thanks for posting this info

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Misperceptions still surface from time to time.

Wasn't glaser kindof the original frangible round ?

And it was called a "glaser safety slug"
Having the word safety in the name probably lead to the misconceptions OR maybe they really did believe initially that these things would be safer to use in buildings and such.


EDIT: After googling "glaser safety slug" It seems those are maybe built slightly different than the rounds you were firing. Don't know if they penetrate any less...

The Glaser Safety Slug bullets are/were indeed significantly different from the composite bullets of the type I tested. The ones I was familiar with consisted of small lead shot contained in a capped hollow jacket. They were intended to break up very easily, including in flesh. They have sometimes been referred to as “prefragmented,” but that’s not really correct because they don’t fragment until they hit something.

If Glaser rounds are still available in rifle versions, they would probably be the least likely to remain dangerous after striking building materials. The criticism of that ammunition, though, that was raised decades ago is its very limited penetration and therefore poor wound ballistics. Shooting someone with virtually anything is usually effective in ending threats*, but the ballistics gurus want us to understand that that’s not always the case and sometimes adequate penetration is necessary.

* Note that biceps boy in Kenosha quickly decided he didn’t want to kill anyone any more after just being shot in the arm—something that some people would scoff at and dismiss as merely a “psychological” stop.

A YouTube test of another type of frangible ammunition through light barriers.

https://www.youtube.com/watch?v=h5_ZidYxbSE

I have personally shot a .40 cal frangible into old level II body armor and the round was fully intact.

Of possible continuing interest.

When I had a blood lead level issue I switched to lead free ammo. Which for 5.56 include a bunch of the issue XM556NT1 rounds. Having shot lots of stuff with it, if it doesn't hit steel or masonry it is simply not frangible. Some odd things that don't have it disintegrate are tires, sand, ballistic materials (soft). I actually didn't try a ceramic plate but I might if i get inspired again on testing.

Those are both pretty high velocity loads. I wonder what would happen in a test with lower velocity loads like 9mm. Great post BTW.

Interesting. Thanks for testing. Is there any data that compares 9mm fmj vs hp?

Someday, maybe I can replicate this type of testing. Various combinations of Drywall, 2x4, double pane glass, curtains, backs of chairs with 9mm and 223.

First hand experience may be good.

Frangible is an excellent choice for shooting gophers in your basement.