We simply don't know based on the forensic evidence how many shots were fired.
Three shells were found in the Sniper's Nest.
CE-399, which was fired from Oswald's short-rifle, is, from all appearances, missing the same amount of lead core as the combined amount that was either removed from JBC's body or left in place inside it.
CE-399, and only CE-399, can account for all seven non-headshot wounds sustained by JFK and JBC.
The largish bullet fragments found inside the limo were ballistically traced to Oswald's short-rifle.
The autopsy doctors said the bullet that penetrated JFK's skull did do near his External Occipital Protuberance, the thickest part of his skull. This explains why that bulled fragmented.
CE-399 was traveling only about 900 feet per second when it struck the radial bone in JBC's wrist, which explains why it didn't fragment more than it did when it stuck it.
The majority of witnesses, including the three TSBD workers immediately below the Sniper's Nest, heard a total of three shots.
However, we do know that if there were more than three shots fired, there were multiple shooters.
Finally, a logical assumption!
The problem for CTs is . . . only three shots were fired, and they were fired over a total of 10.2 seconds.
The SBT was born months later after it was confirmed that at least one shot missed the limo.
Fine.