This article or another on the incident, described it as replica of a .45 calibre pistol.
Doesn't the phrase 'bent open' imply that it is cocked?
Or did they mean to imply it was a .45 caliber revolver?
Most likely, it was one of those cap pistols that accept the disc of caps. I have seen some that break down like the old Webley style revolvers.
There's a cheaply made dart gun which looks like a 1911. You load the darts by tipping the barrel downward. You then pull the rear of the slide back to cock it.
"Bent open" is a totally ambiguous phrase. If it's a semi-auto and the slide's locked back a kid could view that as "bent open" even more than he'd so view it if the slide was closed and the pistol cocked. With a revolver, like the one you show, the phrase could mean opened to exposse the rear of the cylinder.