I am of the firm opinion that 3 shots were fired from the 6th floor of the TSBD (although not by Oswald).
A major problem for this opinion is the amount of ear-witnesses who heard shots coming from the west of the TSBD (railroad/grassy knoll area).
In her WC testimony, Geneva Hine describes how intense the sound of the shots was in the building:
Mr. BALL Could you tell where the shots were coming from?
Miss HINE. Yes, sir; they came from inside the building.
Mr. BALL. How do you know that?
Miss HINE.
Because the building vibrated from the result of the explosion coming in.
Mr. BALL. It appeared to you that the shots came from the building?
Miss HINE. Yes, sir.
Mr. BALL. Did you know they were shots at the time?
Miss HINE. Yes, sir;
they sounded almost like cannon shots they were so terrific.Hine was on the second floor so the sound on the 6th floor must've been even more intense.
The pic below is taken from the Ted Hughes film and shows the south-western windows of the 6th floor open to their fullest extent.
Might it be possible that the sound of the booming, reverberating shots ("like a cannon") exploding out of these windows gave ear-witnesses the distinct impression the sound of the shots was coming from the west of the TSBD?
Just a thought.