"Statistics" also say incidents of such a nature are not likely to happen to "you".
Personal experience on the other hand, says that it can (and did) happen to "me". Personal experience also says, that a bigger gun and meaner attitude saved the lives of me and my entire family. Lucky enough that the trigger never needed pulling.
The question is not a legal one, it's a logistical one. How is one to defend against armed invaders/attackers, if one is not armed? When my life, or the lives of my family are in jeopardy, the one thing I'm not concerned with at the time is whether or not I'm breaking a law that could cost the lives I'm trying to defend, all in the name of some government bureaucrat thinking he knows what's best for me better than I do.
I will say this to my fellow farmers. Do what you think is right for your situation, just don't assume anyone else is going to save your ass when something goes down. It's up to YOU, and only you, to save yourself and those you love when a threat is present. The police are not public servants. They're not personal protection, or any form of security service. They're one and only duty and responsibility is to Enforce the Law, and since this isn't Minority Report, it's not possible for them to do so before it's broken. Therefore, cops arrest people and issue citations. They don't render aid, or come to your rescue. If your existence is prone to dangerous threats to the safety of you and your family (which it is, we all are), then YOU are your first and only line of defense. Be prepared, in whatever way you see fit, but be prepared.