I can't tell what you are suggesting here but...
The gun thought to have been used, would have required the shooter to have done a goodly amount of practice. You can't just have this gun handed to you and be expected to assemble, load, and use it as the shooter did in the video. Shooting under any kind of stress, including wanting to kill and get away immediately, requires proficiency. MOO personal experience
"This is not a common firearm," firearms expert Steve Wolf told
Newsweek. "Very few were manufactured,
Investigators believe the gunman used a rare, integrally suppressed pistol, possibly a Brügger & Thomet Station Six.
www.newsweek.com