Again, could you explain why these dedicated conspirators, who (you admit) were desperate to ensure their ruse of a single gunman worked, planted the wrong type of rifle?
And please assess the probability of that versus people making a simple mistake in the heat of the moment.
Apparently, in your world, there are two groups - those who tell the truth, and those who lie. There's no room for people who make mistakes, who forget details, or who otherwise try to tell the truth, but don't quite do so.
I'm reminded of the Paul Bernardo investigation in Canada, where police spent months fruitlessly searching for a black Trans Am, reported by two witnesses as being involved in one of the kidnappings. Now, it turns out Bernardo didn't own a black Trans Am - he owned a black Nissan which very similar in appearance to a Trans Am. Do you plan to protest his conviction, because if witnesses SAID it was a Trans Am, it MUST have been a Trans Am, and no other type of car is possible?