AFAIK, you'd need a seperate object of the gun, then when the unit is blowen up (Exploding body scripts do this), the gun is remeoved from the person, and the object is created, and set velocivied..
You wouldn't really see it either..
Oh, theres a addon thing on OFP.info (Will be on an archive page, not long ago, but off the main page) that lets you shot soldiers helmets of.. That's your basic idea
- Ben