Because of the misaligned scope and
if the rifle were stolen from the Paines garage
then
1. Somebody had to have had prior knowledge the rifle was stored in the garage and exactly where it was stored in the garage. Who knew? Ruth Paine, Michael Paine, or Marina Oswald, are the most probable persons, unless Oswald had one the conspirators as a temporary friend, like maybe George De Mohrenschildt.
2. The rifle must have been stolen that very night of Thursday Nov 21st or in morning hours of Nov 22 probably about 3 am, because stealing it earlier that week, surely the conspirator would have had several days to practice with the rifle, and align the scope and zero it at 100 yds. (note: Also, stealing the rifle earlier that week would have been taking a risk Oswald discovers the rifle is stolen and reports it before Nov 22).
3. The intention was to fire a couple of shots from this MC rifle at the SE window, hoping to get lucky and hit JFK, but to be certain, at least a 2nd shooter was also on the 6th floor at the SW corner window or the immediate nearby West side window, with a 30.06 rifle with large scope to get the kill head shot at Z313.
4. The SE shooter after shooting 1st shot at Z223 and hitting JFK in the back, reloaded and it took about 4 sec before he was able to attempt 2nd shot, which missed, approz Z290., that round probably striking the asphalt or the curb near Tague.
5. The 30.06 shooter was tracking the JFK limo from the time of the 1st shot attempt by the MC rifle shooter, and after the 2nd shot by the MC shooter at Z290, the 30.06 shooter fired his shot at Z313 just about 1 sec aftewards. This combination of MC shooter and 30.06 shooter, produced 3 loud sounds, with a spacing of 4 seconds and then 1 sec apart between 2nd and 3rd shots, just as Lee Bowers and other earwitness heard.