Il-2 Mod. 1943 bailout

[AWC]

Hi all,

 

This is just out of curiousity. When the bailout occurs, the pilot jumps out fine, but when the gunner tries to bail his canopy stays on its mounting. From what I've read it would've been nearly impossible to manually lift a large armoured canopy especially while not in control of a damaged aircraft, and it is also cumbersome for escaping. So why is it modelled to simply swing open and not jettison?