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One of the things we did this week at the Crimson Trace / Ruger / Safarilant / Leupold / DoubleTap Gunsite event was shooting through intermediate barriers. Part of that was shooting through a windshield to see how much a bullet will deflect (change direction) when it moves through that rather tough piece of engineering. But as we found out, the answer was “not a whole lot.”

We were using DoubleTap’s Bonded Defense series of handgun rounds, and every single one had a very minimal deflection when shot head-on into the car’s windshield. In fact, any deflection we saw could be attributed to shooter error. There was however some considerable loss in energy going through the barrier, with only the 45 ACP and 5.56 ammunition zipping through the rest of the car as well as the dummy — the others we recovered in the rear windshield.

Moral of the story: use 45 ACP if you’re shooting through a windshield.

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  1. A DGU through a windshield might be a challenge for your attorney to deal with, even if the vehicle is about to run you down popping the driver won’t stop it from hitting you.

    • Associated Press, 12/06/12, San Diego: Authorities say 32-year-old Valeria “Munique” Tachiquin Alvarado fled a friend’s apartment in Chula Vista when Border Patrol agents came with an arrest warrant for someone else. Police say her car struck one of the agents and she drove with him on the hood for about 200 yards. He fired 10 times from the hood of her car as he tried to get the woman to stop. The autopsy report says the mother of five’s blood had some methamphetamine and cause of death is listed as multiple gunshot wounds.

        • Exactly my point. Unless you are a super citizen there isn’t a reason to go through a car window from the outside.

  2. So you’re recommending we use ammunition that will go through everyone in the car and everyone standing beyond the car as well? The whole point of using JHPs is to prevent over-penetration.

    • I don’t know about tests with the .357 Sig specifically. The physics are pretty straight forward: velocity isn’t important, weight is. The heavier the bullet, the less a barrier at an oblique angle will deflect the bullet. That is why .40, .41, .44, and .45 calibers are king because they shoot heavy bullets anywhere between 180 grain and 300 grain depending on the specific caliber and bullet combination.

      Since the .357 Sig was optimized around the 125 grain bullet, I suspect it will not perform as well going through windshields on an oblique angle.

      • Well let’s see, the 5.56 these days goes around what, 68 grains? And it did the job…..

        Actually, if I recall correctly, that’s what the .357 Sig was made for. I might be wrong :).

  3. What about the other way…from the car OUT?? Say target is 40 Feet away? I believe you will get much more deflection but will still scare the crap out of the guy aiming at you.

    • LAPD had an incident where this occurred. Officer in unmarked car shooting out at a suspect who pointed a pistol at him. LAPD officer using a .40 S&W, first couple of rounds deflected pretty significantly with one going down into the dash/firewall.

      Of course, officer under stress so hard to reconstruct exactly how his weapon was positioned as he fired.

  4. @Rokurota… Was wondering that myself! I carry a 1911 in .45acp with Hornady TAP FPD 200gr +P’s alternated with 180gr Hornady Critical Defense.
    Love the .45 round but….lot’s of penetration if you had to shoot into a car. I reload so am now wondering about dropping the powder charge just a hair and see how that changes penetration.

  5. What about at an angle? I would think even a 5-10 degree up angle would make penetrating the windshield significantly more unlikely. All the midget concealed weapon carriers should take note.

  6. The FBI test protocol offsets the windshield glass, and places the shot from the perspective of standing to the right front of a car. The set up mimics an officer standing on a sidewalk or on a freeway shoulder like they typically would on an enforcement stop. The level of deflection for a good LEO 180 grain .40 Smith JHP round (Golden Saber or Winchester PDX) isn’t much.

    However, penetration through a windshield significantly deforms a bullet. If a person were to shoot through a windshield at a target 10-15 yards away (as in shooting from inside a car), the result would be a drastic reduction in accuracy. It would still be possible to hit a man – sized target, in my opinion, but it would be a challenge.

    I choose most of my self defense ammo based upon barrier penetration – because this world is full of barriers such as drywall, heavy clothing, glass, etc. and BGs will probably use them. Good ammo in 9mm, .40, and .45 all tend to do well against them provided the JHP in question is made well. I’ve yet to try Hornady Critical Duty, but the design looks solid.

    • Well as far as the Hornady Critical Defense and TAP FPD they seem to have good penetration. I shoot these out of a 3.18″ match grade bull barreled 1911 compact and an Auto Ordan

  7. I enjoy visiting this web site because the contributors give us information we might not otherwise obtain. In this case, it will not change the type of ammunition I choose for every day carrying. Anybody receiving ANY type of round (in a vehicle) will likely be gravely injured, unless it’s from a pellet gun.

    If SHTF I would definitely remember this information, perhaps start using FMJ. As it stands, the risk of causing collateral damage is simply too great.

  8. The most likely scenario for an armed citizen to be shooting into a car is a kidnapping situation where a criminal is trying to drive away with hostages (family members) still in the car.

    Of course there is substantial risk to the hostages if you have to shoot into a car at a criminal trying to drive away with hostages still in the car. In my mind there is much greater risk to the hostages entrusting them to the criminal who had no qualms about stealing your car, doing it by force, and driving away with hostages.

  9. Texas DPS used to issue the Sig P220 .45 when they first switched to semi auto pistols. Since they are the highway patrol, most of their shootings involve automobiles. They were not having much luck with penetration of automobile bodies so they started testing other rounds. They now issue the Sig P226 in .357 Sig.


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