Article: What Really happens when bullets “skip”? by Rob Pincus


Great article from Rob Pincus. 

Article from I.C.E. Training Updates (http://www.imakenews.com/valhalla/e_article000423482.cfm?x)

July 5, 2005 

What Really happens when bullets “skip”? 

by Rob Pincus

“Don’t run the walls” and “Don’t stick your weapon/hands/body beyond cover” are standard points of instructions when it comes to tactical training. Often, instructors will explain that “bullets follow the walls” or use some other easily understandable concept to convey why these things are important. 
At Valhalla we go a step further… demonstrating with live fire and lead rounds just exactly why staying off of hard walls and keeping everything back from cover is so important. A quick note of caution for everyone reading this: while the fundamentals of ricochet and skip are understandable, when you start purposely firing lead slugs at flat steel surfaces, chunks can fly off in any direction. This is not a demonstration that should be conducted without the utmost caution and significant forethought.
First, the concept: The harder and flatter the surface and the lighter the slug or fragment, the closer the angle of incident will be to parallel with that surface. What exactly does that mean?  Well, for one thing it means that the angle of attack (the angle at which the slug strikes the flat surface) is hardly important in the outcome of the skip or ricochet. The angle of incident (the angle at which the slug, or pieces thereof come off of the surface) is influenced much more by the mass of the chunk and the nature of the surface itself. For the demo, use flat mild steel as our surface and WinClean brass jacketed rounds. This combination give us the most consistent demonstrations of the concept in action.
 
On our indoor square range, we arrange target stands with flat steel backs side by side, perpendicular to the rubber faced primary impact wall. At the end of the row, we place another target stand at about a 45 degree angle, with a photo-realistic silhouette target on it, representing a bad guy using cover very poorly, by extending beyond the flat surface (corner of a building, sheet metal of an SUV, etc) of his cover.

Starting at about a 75 degree angle, I shoot the steel about 5-8 feet from the target. This usually results in a body hit on the silhouette and sells the point pretty well. Next, I’ll move laterally along the wall, about 10-15 feet away, shooting both sharper angles on the steel and further away from the target. During demos with students, I’ll get to about 70 or 75 degrees and up to about 15 feet away from the target, consistently skipping rounds into the body cavity. As the angle of attack increases towards 90 degrees, even the heavy jacketed WinClean starts to break up and the risk of less predictable results (and ensuing injury to myself or bystanders) increases. 
After the demo, the students walk the area to get a feel for just how the lead moved. One point that is always brought up is that I was missing the intended target by not only up to 15 lateral feet, but that I was up to 40 or 50 degrees offline from it as well and still getting lethal hits because of the environment
Note that this demo is not done to teach trick shooting, it is done to drive home the points of instruction noted in the first sentence of this article. We conduct this demo during several of our tactics courses and it has never failed to impress the importance of staying off the walls and using cover properly to our students.

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Firearms Instructor in the DC Metro Area

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Posted in Ballistics

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