Since the BG will probably have poor gun handling skills, he will probably have his finger wrapped around the trigger as he points the gun at us.
This is a dangerous assumption/mentallity to train with. Assuming a lack of good weapon skill in this case is like saying that street thugs don't have boxing/fighting/martial arts training when preparing empty hand/non ballistic weapon responses.
Thus even if he doesn't try to shoot us on purpose, we should resign ourselves that he'll probably have an accidental discharge (e.g. startle response or interlimb interaction) when we begin our disarm.
Always assume that you will be wounded by the weapon in play. Knife,gun or other. I agree.
Something that shoots, e.g., airsoft, helps us train with something actually coming out of the gun. Coupled with good "acting" and intent from your training partners, airsoft/simunitions have taught us much about the realities of pistol disarm scenarios. Any technique must have getting off the line of force as the very first step. Anything else and you'll most likely get hit (which is considered poor form

).
Take care. :asian: