Ideally you'd want to use a gun which didn't fire that fast; like a nice 18 inch Cannon. Then you wouldn't have to bother about making a small exit wound so it looks like suicide; the cannon would remove all but the most grotesque evidence.
A Knight is sworn to Honour. His heart knows only Virtue. His blade defends the helpless. His might upholds the Weak. His word speaks only truth. His wrath undoes the Wicked.