Walt has suggested previously that there was no one in the SE window because the MC rifle seems to be underneath pallets and unfired.
IMO it’s more probable there WAS a shooter at the SE window who used a semi auto rifle and fired those 3 shots in 4.8 secs , just as Harold Norman replicated the spacing and just as Norman described the sequence as hearing 1st shot, and seeing the president slump and then hearing 2 more shots rapidly fired
The “Klak klak” noise was from shells hitting and bouncing on the floor and NOT from “bolt action” although a semi auto rifle might possibly have noise from bolt action too
The dilemma here is Arnold Rowland who sees some kind of rifle with large enough scope that he can see it from over 100 yds away , yet the SE rifle seen sticking out the window by Euins, Malcom Couch, Bob Jackson, Brennan, there is no scope visible