I had a debate with the resident know it all at work today in regards to weither bullets pass straight through autoglass when they hit the glass or if they deviate on an angle. This Officer (and FORMER firearms instructor) said that he went to a 3 day school 10 years ago and that the bullets pass straight through. I went last year to the Sigarms academy bullets and vehicles course. In addition to watching the instructor demonstrate the approx. 12 - 18inch (high) deviation from his point of aim (using a lasermax internal laser) and the point of impact on the target, which was placed right at the bumper, we all shot through the windshield while seated and from outside the car and the bullets went 12 - 18 inches high when seated and low when shooting into the car from outside. The only time they went straight through, was when you shot several rounds through the same spot and it opened up a hole in the windshield. Does anyone here have any training or real world experience that indicates anything different from what I experienced at Sig? I am open to the guy at work being right, but his atttitude and cockyness made it heated, combined with my experience being different. thats why I am posting here. Thanks!
Your friend sounds like the normal work know it all… my training partner went to an ITTS (Scotty Reitz) vehicle assualts class and his experience was very close to yours. While at another ITTS class myself we discussed the matter and Scotty related your same experience (but without the live fire to back it up).
I think you should bet your partner to rent a vehicle and have you both train on it. If your right then he pays the cost… 
Tim.
Not sure if this website has been discredited before, but they have a couple posts about this exact topic.
http://www.theboxotruth.com/docs/buickot1.htm
http://www.theboxotruth.com/docs/buickot2.htm
Hope it helps.
If he’s talking about the tempered glass used in the side windows and perhaps the rear window (although there are no guarantees there…) then yes, it’s likely the bullet will go straight through.
If he’s talking about laminated windshield glass then he’s on crack. Bullet deflection is a SERIOUS problem when it comes to shooting through windshield glass.
Bonus points to the person who can name the M4Carbine member in that picture…
Who? Robb? And that’s Kyle’s glove on the left.
I can attest to the 9mm deflection from the outside…
http://www.theboxotruth.com/images/buick/buickwshieldo1.jpg
M_P
Bingo. That’s me in the drivers seat!
Thanks. I forgot about that website. I wish I remembered that today at work. Funny thing I found that website right before I took the class - I felt like I deprived myself of learning that at the class, LOL.
A brief note about the Buick O’ Truth:
The goal of documenting the car shoot at Blackwater was to try and dispel some myths and bring some understanding to a larger audience who had little or no experience with vehicles as an intermediate barrier or as a piece of cover. I’d done several vehicle shoots at BW prior to the one documented here and the results were basically the same as what you see on the Buick.
That shoot is not meant to compete with the sort of research that DocGKR or other professionals do…although unfortunately I sometimes see that individuals read more into that shoot (and some others listed on the Box O’ Truth website) than they should. I don’t bat in that league, although I think the majority of the conclusions I reached in that writeup are in line with what the real experts will tell you…I’m certainly open to correction if any of them are wrong.
The Buick shoot was well received by most, and extremely controversial among some because I happened to mention that the PS90 didn’t do terribly well when one of the AI’s shot the car door with it. (most people were loading mags at the time…I was still at the car with the camera) Things did not improve when I related that some SWAT officers from a large metropolitan PD detailed some spectacular failures they had experienced with the P90 in OIS incidents.
Some good came of that writeup, however, as it got me talking to Hawkeye (of course, talking to Hawkeye cost me money…) and Robb invited me to check out this site. I still owe Robb a steak for the invite…and a steak for hooking me up with a replacement striker. Next time we meet up I hope you come hungry, bro…
Of course, I should have said no bonus points for the subjects who are actually IN the pictures…that goes for Mr. Business Casual too. 
Why, is that you in the wing mirror?
M_P
A few years ago we hosted a sniper match with a stage where shooters would engage the driver of a vehicle from an elevated position shooting the driver through the windshield of a motor vehicle. We obtained dozens of curved laminate automobile windshields, set them at angles typically found on motor vehicles, and positioned IDPA targets behind the windshields at a distance representative of a driver seated in a vehicle. 30 of us fired 5 rounds each at the driver for an attempted head shot with the ammo they brought for the day and each shooter started with a fresh windshield. Most ammo was 5.56mm and 7.62mm match, ball, HP and TAP. Later several of us tried shooting from various angles and distances with handguns in .45 ACP & 9mm while we were on the same plane as the vehicle glass. All rounds deflected, some more than others, and none could be counted on to strike where intended. Many rounds missing by several inches and some missed completely. This is a very narrow perspective and far from scientific, but our conclusion was that no round used that day could be counted on to strike the target with any degree of certainty.