Automobile glass deflection of HG rounds

[DogMan 2,343]

Something that crosses my mind every once in a while is what kind of accuracy I could expect from a pistol round (in my case .40) if I were forced to fire from inside a vehicle with no opportunity to roll down a window or exit the vehicle. This would be a rare scenario such as being approached by a gun wielding carjacker or robber while sitting a stoplight or something like that. Is there much deflection at all, or is it highly dependent on what angle the round strikes the glass, is the energy of the bullet powerful enough to overcome any deflection, or what? Obviously one round through a window or windshield would make getting off the next round more difficult due to visibility through the shattered glass which makes accuracy with the first round that much more important. I'm just wondering if anyone has read anything or knows anything about this at all.

[Klassy Kalashnikov 1,393]

The Box o Truth did a 2-part thing bullets vs. auto glass, both outside/in and inside/out.

 

http://www.theboxotruth.com/docs/buickot1.htm

http://www.theboxotruth.com/docs/buickot2.htm

 

Also, I remember reading that the Hornady Critical Defense rounds do very poorly against auto glass, manufacturer confirmed it as well.

 

Hope that helps.

[DogMan 2,343]

The Box o Truth did a 2-part thing bullets vs. auto glass, both outside/in and inside/out.

 

http://www.theboxotr...cs/buickot1.htm

http://www.theboxotr...cs/buickot2.htm

 

Also, I remember reading that the Hornady Critical Defense rounds do very poorly against auto glass, manufacturer confirmed it as well.

 

Hope that helps.

 

Wow, that's excellent. Exactly what I was looking for. I guess the answer to my question is that I need to aim a little low, which seems counter-intuitive, but the photos speak for themselves. Thanks.

[Shandlanos 1,470]

Another thing to consider is jacket separation. Gold dots are supposedly designed to prevent this from happening when they go through glass or clothing.

[DogMan 2,343]

Another thing to consider is jacket separation. Gold dots are supposedly designed to prevent this from happening when they go through glass or clothing.

 

That's probably true but this would be such a rare possibility that it wouldn't be feasible to have a specific round in the chamber in anticipation of it happening. It's more like "how do I make the best of whatever I happen to be carrying at the time." Now if I made a living driving through bad neighborhoods and such I would have to seriously consider that. I appreciate the info.

[elia.jon1 1]

from what i understand the front window is the only problem, if you have a fancy back window it might too....

 

but i think box o truth said a .22 lost no velocity going thru both side windows

[Shandlanos 1,470]

from what i understand the front window is the only problem, if you have a fancy back window it might too....

 

but i think box o truth said a .22 lost no velocity going thru both side windows

 

The laws of physics say otherwise.

 

The projectile has to deposit energy into the glass to cause it to break; that energy deposit might only deform the projectile minimally, but it will definitely result in at least marginally reduced velocity.

[elia.jon1 1]

from what i understand the front window is the only problem, if you have a fancy back window it might too....

 

but i think box o truth said a .22 lost no velocity going thru both side windows

 

The laws of physics say otherwise.

 

The projectile has to deposit energy into the glass to cause it to break; that energy deposit might only deform the projectile minimally, but it will definitely result in at least marginally reduced velocity.

 

 

 

What about the door window glass?

 

Utterly inconsequential ballistically.

 

Anything will shatter it without causing any bullet damage, even a .22.

 

To demonstrate the difference here, a 60 grain .22 LR fired from inside the vehicle won't even penetrate the windshield.

 

That same round can pass through BOTH side windows without even slowing down.

 

^^^

that is a quote from the box of truth web page, it was what they said, i just repeated it.....

and i kind of believe those old bastards

[crackback 135]

Auto glass....penetration... sounds like a job for 7.62x25mm Tokarev...

[IndyArms 10,186]

My personal conundrum... Get a Brinks armored truck... and a 50 BMG... and then some standard steel core ball, and some AP, and see how well they perform against the "bullet proof" glass of the truck... I would just love to know what they would do to THAT glass... would it stop the rounds? Would they punch through like butter??

 

( My guess is the butter aspect... LOL )

 

 

Just curious... I wouldnt be surprised if anyone KNEW the truth on THAT one... and I sure as heck dont plan to FIND OUT firsthand... LOL

 

 

 

 

[elia.jon1 1]

indy, i drove armored trucks for over 5 years, and one day i accidentally kicked out the front windshield of one of the trucks....anyways most of it is level 3.....so it shouldn't be able to take 30-06....but that level 3 glass is better than the rest of the truck i guarantee.....

 

 

 

 

 

also look at pics of the brinks truck robbery and you will see the glass didn't really stand up to sprays of ak fire...

Edited June 8, 2010 by elia.jon1

[Graniteer 10]

SIG Sauer had a special about this not that long ago. It was on the Outdoor Channel I think, they taped one of their training scenarios.

 

No matter what they shot the windshield with (9 mm, .223, .40), it still deflected, sometimes at weird angles. The dude inside the car couldn't shoot a target 10 feet off his bumper. You have to shoot the windsheld a bunch to break it up so it loses rigidity. It was pretty nuts, I didn't think it would have that much of an impact.

[DogMan 2,343]

Here is a video that shows some fairly good accuracy through the windshield with a close up target. According to the shooter's comments he shot about 3" high with a 9mm and was dead on with everything else. Type of ammo was not specified.