What energy do you need to take out windshields?

[osbornk]

WWB 9 mm, Blazer 9mm - both in FMJ go through windshields without a hitch.

No. They usually or may go through windshields because there are many variables, including the angle the bullet strikes the windshield. All winshields are not the same. The thickness of windshields vary, depending on what the car manufacturer is trying to do. They use various thicknesses to control the noise level or to adjust the overall weight of the vehicle. Also, as my brother that owns a body shop found out, aftermarket windshields by different companies can have thicknesses differences.

[Glenn E. Meyer]

Having shot a pretty standard car windshield or two with a direct angle, they go right through. Now if you shot a glancing blow, they will bounce off your head also.

Next, I've shot targets behind a windshield in a car. If you hit straight on, the round usually travels pretty straight into the target. Again, these were various 9mm FMJs.

[TailGator]

Me: I would be interested in putting a target behind a windshield to get an idea about how much deflection occurs. Any chance you were able to do that? I haven't, and have no prospects of doing so.

Dr. Meyer: Next, I've shot targets behind a windshield in a car. If you hit straight on, the round usually travels pretty straight into the target. Again, these were various 9mm FMJs.

Thanks for the info. Interesting result.