Frangible ammuniton vs car
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Most frangible ammunition is made by compressing copper powder (either pure or with tin and/or polymer added) into the shape of a bullet on a machine basically identical to the kind used to manufacture medicine tablets. When a frangible round hits something hard — a steel plate, a rock, etc. — POOF! It transforms back into dust.

But just how easily does that happen? Does frangible ammo return to dust if it hits something like a car door? A window? A tire?

To find out, Nick and I hit the range with a box of Sinterfire 9mm and a garden variety GLOCK 19. The results surprised both of us.

If you’re at work or just don’t like watching videos, here’s the spoiler:

The frangible 9mm zipped through one car door, through the door card, through the other door card, and sometimes exited the door on the far side of the car. The bullet shed copper the whole way — it entered the first door at 9mm and exited the second one at maybe 4mm…who knows? But it appears to have stayed quite deadly the whole way.

A frangible round zipped through the trunk and through the rear seat, with a couple of small chunks remaining in tact enough to puncture its way into the front seat.

Another one made it through both sidewalls of a steel-belted radial tire and punched through the plastic wheel well liner.

One made it right through a cast aluminum valve cover. What it did inside there or how much solid projectile was left, if any, after breaking through, we don’t know.

Interestingly, the frangible 9mm didn’t like vehicle glass. Even shooting at the pre-fractured safety glass of the rear window, the bullet was reduced mostly to dust and possibly a few chunks, though the damage we saw from “copper chunks” could have been caused by flying glass, too.

Laminated windshield glass also appeared to mostly destroy the projectile. At least, it certainly turned much of it into dust. Certainly more than the sheet metal did.

So there you have it. Once again, we find that a car provides concealment, but not cover unless you’re behind a solid chunk of metal like the engine block, hubs/brakes, etc. Even if you’re facing frangible pistol ammo.

Nick and I were surprised to see this kind of ammo pass completely through two car doors. We wouldn’t have guessed that a pane of automotive glass, whether window or windshield, is actually better at turning a frangible projectile back into dust than steel body panels, but there you go.

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52 COMMENTS

  1. Thanks for the post. Interesting.

    I’m not surprised.

    If it would that easily tangible, it would begin desintergrating as it left the cartidge case.

    Lotta friction and force inside a barrel.

    • Specialist, not suprised either. Frangiable ammo was meant to dissolve on steel and backstops with no lead residue. Laminated windshield glass is very hard to penetrate with .223 or any handgun caliber unless it’s a bonded core bullet. .30 caliber doesn’t seem to have the same problem. Actually, handgun calibers tend to do better than M193 ball on windshields. Never would have believed it until I spent a few days on the range with Federal, CCI/Speer. Several different times. Spread out over five years or so.

    • frangible pistol rounds?

      They perform like FMJ but with almost no chance of tumbling. They just icepick straight through unless they hit bone.

      Once you get over 2000fps things start to get interesting, though.

      • Ya ain’t gonna get much above 1400 fps with 9mm, so you must be referring to rifle cartridges, in which case why bother with frangible?

        • Depending on location may be all the common caliber ammo available in meaningful quantities. Would still prefer more 193 but wouldn’t turn down XM556NT1 if I ran out.

        • Frangible rifle has its uses. It WILL stop in a body and make a mess of it, and it’s so fast and so light that drywall will tumble it and it stops soon after.

        • Sian thanks for the feedback I remember the 50 grain stuff we used (once) seemed to hover right around 3000 fps for both the m4 and m16 and from internet reviews seems pretty consistent for 16 and 18 inch barrels as well so I can see a use for indoors other than popping Ivan’s.

        • Stuck with 16 inches and I know the 50 grain version we have available is pretty steady around 3000 fps for 14.5 – 20. On further review looks like it would be an acceptable backup for 193 for my general area and likely issues.

    • Re: what does frangible to to a human body?

      I have seen a few gel tests. Look them up.

      The bullet appears to explode on impact. Some pieces travel through, but lacking enough mass, most stop short of over-penetration. Much of the sintered copper is deposited at the point of impact to a depth of about 3″.

      It may not kill, but there is no surgeon on Earth that could find all of the copper. Flesh around copper doesn’t heal – it continues to bleed.

      And I pray to God that I never have to use this knowledge.

  2. Hardness rather than strength of the impact surface appears to be the key. Sheet metal is much softer and more ductile than glass.

    • I always forget how much harder glass is than steel. I should know by now but perceived durability gets in the way

  3. Wow.
    It’s about the only ammo I’ve seen (in 9mm) of late.
    Price was kinda steep too.
    This is fascinating.

  4. I wonder what type of ammo Air Marshals carry, and what their testing results look like. I’ve always assumed they carry low velocity frangible…

    • I don’t know what it is now, but it used to be .357 Sig HPs. They fully expected the round to over-penetrate, and counted on it. The reality of having to shoot through the hostage to get to the terrorist was well understood.

    • Last I heard over a decade ago it was something (likely proprietary) in 357 sig. I am sure they have some neat options now.

    • It was .357 SIG in the USA, but it varies depending on whom or on what country the air marshals / sky marshals are working for. ie, they’re not all Americans. I know some of the others carry guns chambered in 9mm and .40 S&W. The other guys who are commonly armed on international rides are diplomatic security.

    • Not surprising, it’s a polymer of some sort binding the powder together, so the friction down the barrel and the hot gas driving it would melt and burn it…

      • The Sinterfire doesn’t use polymer, it’s formed using pressure and heat, and it makes tons of dust when firing, and even more at the target.

        The copper-polymer rounds run cleaner than that and particles don’t stay airborne. They do give up a little weight to the polymer though.

  5. There’s a lot of empty space inside a vehicle door. The average one has a couple switches in the arm rest, a latch mechanism, a wiring harness, a couple stamped steel arms and/or cables, and a small electric motor. If the window is down, it will also have a sheet of tempered glass that is pretty brittle and shatters into a bunch of little chunks. A soft sheet metal skin on the outside, a stamped sheet metal framework, and a cardboard/plastic inner panel. Some have a layer of thin sheet plastic to help deaden sound. Really not much more protection than two or three trash can lids, unless the slug happens to hit the window motor or latch mechanism.

  6. It generally takes something harder than the projectile to actually get it to disintegrate. No different than a lead projectile. Or one with a coper jacket. Its just that a frangible projectile is less deformable than lead, and slightly less hard. Basically it is designed to lose all integrity once it hits something really hard.

    But a steel automotive body panel is not “really hard”. It’ll just cause it to shed some material as it passes through. Automotive glass on the other hand is very hard. But extremely brittle. That’s why windshields have a layer of polymer between the two sheets to hold it together if it breaks. Steel targets and steel body armor is significantly harder than the mild steel used to make a thing automotive body panel.

  7. For other ideas, how about difference sizes of buckshot? What’s the minimum size to go through one door, two doors, windshield?

  8. Lot of videos out there on the resilience of tempered glass. Perhaps make those frangible bullets or shot gun loads with some coarsely ground spark plug porcelain.
    See what that does. Laminated glass, sounds like would be another story, don’t know.

  9. Heh heh, reminds me of when some German exchange students came out to my old place. Me,”You guys want to shoot some gunms?” ,,”What are we going to shoot?” they said. Me “This car.” ,,,”Your going to shoot your Auto? ” ,, theyd never got to shoot gunms before but it wasn’t long before they were having a blast. Also showed them the difference between movie and for real. Shooting cinder blocks, refrigerators, wood, and a couch. They picked the SKS as their favorite, don’t much like the Weatherby or Springfield, looked in dicust at the AK., ,. Your going to shoot your auto

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