Coupla differences I've noted among state 'castle' laws:
- In some, entry must have occurred; in others, an unlawful attempt will suffice
- Entry must be made or attempted with force in some states, but not inothers
- In some but not all, the defender must be defending an occupied residence
Don't rely on the letter of the law alone. In Missouri, for example, the supreme court approved jury instructions place a greater burden on the defender than the statute itself would seem to.
Know the law, assume nothing, and don't shoot unless you have to.