Before approaching the vehicle containing Boushie, Stanley testified that the slide on the Tokarev was pushed back, indicating that the gun was out of ammunition.
Under normal conditions, the slide of a Tokarev will indeed snap back into a locked position once the gun is out of ammunition. The video below by YouTuber Hickok45 illustrates the feature: After he has fired all nine rounds of a magazine, at 1:40 the Tokarev snaps open as a signal to the shooter to reload.
However, the slide cannot snap open if the last round fired was malfunctioning, as Stanley’s testimony claims.
The slide needs the recoil of a fired round to snap into a locked position. Thus, even if he was out of ammunition, the only way the slide of the Tokarev could have been in a locked position would be if Stanley had done it manually.
Here’s the important part: Doing that should have safely cleared the gun’s chamber of the misfired round.
A properly functioning Tokarev would have ejected the malfunctioning round when Stanley racked back the slide. Then, when the round suddenly discharged, it would have done so relatively harmlessly on the ground, instead of into Boushie’s head.
So, for Stanley’s account to be credible, his gun loaded with malfunctioning ammunition also had to be malfunctioning itself.