Subject: How do you determine angle of deflection for bullets off concrete

I am police range master and want to teach officers about bullet deflection off 
ground and walls for their safety.  I have read your section on windshields. I 
have experimented with our ammunition and have hit targets but want to know how 
to determine angle deflection on concrete. I am concerned about the path a 
bullet will travel down a wall or across the ground and strike my officers. 
What is the minimum and maximum degree of angle that a bullet can strike the 
wall and travel along the wall?  

Re: How do you determine angle of deflection for bullets off concrete