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Bullets and Auto Glass

NCJ Number
Law and Order Volume: 50 Issue: 3 Dated: March 2002 Pages: 56-58,60
Mark McCardia
Date Published
4 pages
This article presents the results of a glass testing procedure to determine where police officers should shoot in the event of a vehicle stop.
Numerous windshields were obtained from a local junkyard. Wooden braces were cut into triangles to support the windshield at three different angles. The windshields were placed 30 inches in front of the target -- the average distance from the windshield, back glass, and left and right side glass to the driver’s head. The shooter stood 10 feet in front of the glass and took a sighting-in shot at a paper target mounted on quarter inch plywood. The Marion County (Indiana) issue Glock 22s began with the .40 S&W 155-grain rounds. A generic JHP fired bonded and plated rounds, to see if there was a difference. A measurable difference between various designs of bullets was evident. All the bullets that penetrated the windshield impacted lower than the aiming point, which contradicts what has frequently been said about bullets and glass: that bullets shot into a windshield angle up after they penetrate the glass. Results of this glass testing procedure showed the 62 grain Tactical did much better than the 55 grain Tactical, but why could not be determined. A lesson from the testing is that some common .223 Rem bullets completely fragment after glass. With these results, the Marion County Sheriff SWAT made an immediate switch to the Federal Tactical in the .223 caliber. Windshields significantly slow down handgun rounds and handgun rounds are very slow to begin with. That should be kept in mind when selecting caliber, weapon, and type of ammunition. The most important lessons learned were to teach officers to avoid shooting through windshield glass if possible and there is no such thing as an instant stop on a vehicle.