If you plan on attaching an airsoft gun or anything else involving a projectile on the plane, forget it. It is against AMA rules and generally a bad idea these days.

Where will this be flying? Near an AMA field? Near houses, people and property? You need to be careful. You don't want to interfere with a flying site or cause any comotion or damage that could turn people against local RC flyers.

If you goal is something besides shooting and you are in a safe area, I'd look at a cheap electric heli or small electric/glider type plane.