Exactly what do you believe is unreasonable about it?
Do you honestly think a fleeing killer would only eject the shells half way?? We know he tossed the spent shells away, so he wasn't concerned about saving the empty brass.... And since that's true, it's not reasonable to eject the shells half way. He would have ejected them and let them fall on the ground.
It's clear to me that the killer was NOT using a Smith & Wesson.......I believe that he was using a revolver like a Colt or Ruger without a sawed off barrel.... Because his accuracy was excellent.....