From: gwyn@arl.mil (Doug Gwyn )
Subject: Re: bullets and car windows
Organization: U.S. Army Research Laboratory APG, MD.

In article <MCINTOSH.95Feb11221625@helena.rice.edu> mcintosh@rice.edu (Nathaniel McIntosh) writes:
#Here's a question for all you ballistics experts out there: is it
#possible for a bullet to shatter a car window without going into the
#car? This applies to a window made of safety glass, not regular glass.
#There is a story behind this question. Last week my wife was driving
#on one of the highways here in Houston. While negotiating a tricky
#on-ramp, she pulled ahead of a large white car with several men in
#it. The white car then sped up and followed her for a mile or so. A
#little while later, she heard a noise, and when she looked over, the
#passenger side window had disintegrated. The white car had been
#immediately opposite her on the right when this happened; it continued
#on, while she slowed down right away and took the next exit (she
#wasn't able to get a license plate).

Probably it was a broken piece of spark plug insulator, which is the
usual tool of the snatch-and-run operators.  I'm surprised you hadn't
heard about it before.  Try it in a junkyard sometime -- the window
immediately implodes into a bunch of small granules.  (That's the
"safety" aspect of the glass.)

Sharp impact of several possible projectiles will do the same thing,
but the sharp edges of the broken insulator seem to be especially
reliable and effective.

Get her a cellular phone and a carry pistol ASAP, in case she wasn't
just a random vicitm.