I had a couple of thoughts after looking at the MythBusters video and the DeRonja-Holland report posted earlier.
Myth Busters ricochet video. Regarding the pavement strikes.
In the Myth Busters testing (as well as the Haag tests), in real time the pavement strike’s flying debris can visually be seen but then dissipates very fast. It looks to be visually dissipated in a fraction of a second. For example, in the Myth Busters 32deg angle test at time 2:20, if I look right at the impact spot, I can see it happen, but it’s just a very brief explosion with a small puff of smoke off the pavement.
Perhaps this might help explain why only a few people reported seeing a pavement strike in Dealey Plaza. You can easily hear the shot, but if you were not looking close to where it struck, you might miss seeing it entirely. For example, if you were looking at JFK and it hit near your line of sight to JFK you might see it (this might explain the Faye Chism dynamic). If you were focused on Jackie or somewhere else, it might be much harder to see the pavement strike in the periphery of your field of vision.
Just one other observation is that the copper jacketed bullets were only at about Mach 1, but in this test they still fragmented and deformed, independent of the tested shooting angles of incidence and rebound.
DeRonja-Holland report.
If indeed their final hypothesis is accurately depicted in their photograph Figure 20 in that study, then I wanted to comment on why so many I’ve heard saying the missed shot happened because of a mast deflection, may be wrong.
This may have been discussed before, but I thought it was worth noting that their proposed bullet trajectory could just be called a trajectory that would minimally miss the limo if the mast didn't get in the way (but it's not the smallest miss). On the cropped version here there is a magenta colored line from their mast strike point (a white dot) to a circle representing the President’s head as the target. That line length represents an associated aim angle of missing the target. The other line to the lower right at about 4 o’clock is a different angle of limo miss that is a smaller angle of miss depicted by its smaller line length (as measured in pixels) on the photo.
In their final scenario, it appears the real reason for the Presidential and limo miss is simply an error in aiming, not a mast deflection. In their hypothesis the mast just happened to get in the way of the bullet path for that scenario. If the mast was not even there, this shot would still miss the President and the limo by overshooting the limo, and it would miss by a larger margin than a minimum limo miss to the lower right. The mast now becomes their mechanism for disappearance of the bullet. The other smaller limo minimum miss to the lower right would have the bullet striking the pavement with disintegration or possibly some fragment ricochet as the mechanism for the bullet disappearance.
Net, an early missed shot would not need to be predicated on the mast. It could have been as simple as just poor target tracking with associated aim error and could occur at any time around there. Only 15-20 ft further down the road would have had the limo and the President totally in the clear, past the mast and before the tree branches.