A tragic loss indeed. I've just started reading the inquiry report on A9-650 and A9-625, and about the obsolete firing pistols.
Owen, I can't think where else you could go except, as Andy suggested, asking on
RafCommands Forums - Powered by vBulletin for anyone else involved in research into 100 (RAAF) Squadron. I know you are a member of TOCH, but rafcommands also has a tremendous membership who are always willing to help.
The Beaufort File gives no more details other than the one line for the individual aircraft serial.