The Haag ballistics team demonstrated that a Carcano bullet fired directly into asphalt and at the estimated angle Oswald's bullet would have hit the pavement would complete disintegrate and not ricochet. I don't think either a tree branch or the traffic arm would have been in the line of fire when the first shot was fired but because we don't have definitive proof of precisely when that shot was fired, it can't be ruled out.
I wasn’t convinced that a Carcano bullet would not ricochet off of Elm Street by the Haag demonstration.
1). I believe that the asphalt surface of Elm Street is much harder than the piece of asphalt that the Haags used.
2). The Haags’ demonstration used a horizontal bullet trajectory from the rifle to the asphalt. The trajectory from the sixth floor window of the TSBD to the Elm Street surface is about 35-degrees downward from horizontal and the surface of the street slopes downward about 3% also. BTW, this angle is close to the ideal angle for skipping stones across water.
3). I believe that the backstop of the Haags’ demonstration was not tall enough to be able to show a ricochet that might have gone over the top of it.
4). Bullets don’t just disintegrate into nothingness. They should have been able to find and recover some fragments of the bullet. But they apparently were not able to find any fragments. In my opinion, that’s reason enough to believe that the ricochet went over the top of the backstop.