Speer's idea that actual firecrackers might have been used to confuse people about the actual location of the shooters (in his scenario, 2 shooters) would explain 10 of 11 (IIRC) witnesses that smelled gunpowder, and also would explain why some people at first thought they heard firecrackers, puffs of smoke on the Knoll, etc. Of course, the actual use of firecrackers to mask or confuse would be conclusive proof of co-conspirators to the shooting, in a way that even having two shooters in the same small part of town doesn't quite prove. And no one that I know of remembers seeing the sort of debris that real firecrackers leave behind. But it doesn't explain why the guy on the bridge (upwind of all that) would smell gunpowder.
Furthermore, the use of smaller caliber bullets is consistent with the size of the "entry wound" in the back of JFK's skull, and the tendency to fragment demonstrated by the AR-15/M-16 could account for the nature of the skull wound. This isn't new to Speer in the 90's and the 'Oughts, it was proposed by Donaghue in the 70's, although he wasn't called as a witness by the HSCA (even though he was actually in the room waiting to be called).
I think that 2 shots from the TSBD is entirely plausible and consistent with the recovered evidence. I think that silenced gunfire (from 1 location) is entirely plausible. I think that subsonic or underloaded cartridges would explain the pristine bullet and the anomalous "steep-angled yet shallow-penetrating" JFK back wound... however, that implies that the TSBD was the source of the underpowered bullet, since it came in at a greater angle. And it looks like Speer favors the silencer (and subsonic bullets) on the weapon on the DalTex Bldg.
Still, you could have an underpowered bullet from the TSBD and a deliberately silenced bullet from another location. However, custom loaded underpowered M/C 91/38 bullets raises the question of where they might have been acquired (not that we actually know where the clip and the apparently standard ammo that
was recovered comes from either) . Or you could just say the ammo is old and the powder didn't work properly, but if your TSBD shooter didn't
know about the underpowered ammo in advance, he couldn't have corrected his aim. And probably the shot that hit Connally wasn't underpowered. Also you'd need to explain whether the subsonic bullet could account for the devastating head wound. (The AR-15/M-16 fires a supersonic round.)
It seems unlikely that a "burst of semi-automatic gunfire" would have gone unnoticed among the many trained and experienced observers in Dealy Plaza that day. I also fail to see how a shooter on the DalTex Building with one burst of gunfire (Speer's theory) could have fired shots that both slanted markedly downward in the Connally case and had a slightly upward trajectory thru JFK's throat.
I personally think that the shot that hit Connally
did come from the TSBD. And it seems that the MC 91/38 with WCC ammo would account for the wounds and damage Connally suffered. However, like Speer says, and Specter demonstrates, a shot from the TSBD that simply comes in slightly over JFK's shoulder would have the same resultant track as the alleged SBT:
"All that is necessary for tyranny to succeed is for good men to do nothing." (unknown)
James Tracy: "There is sometimes an undue amount of paranoia among some conspiracy researchers that can contribute to flawed observations and analysis."
Gary Cornwell (Dept. Chief Counsel HSCA): "A fact merely marks the point at which we have agreed to let investigation cease."
Alan Ford: "Just because you believe it, that doesn't make it so."