All sympathy with the farmer.
We had a former 'friend' of ours kick our front door in and barge in and start beating my DP with a weapon.
I can tell you I did not stop and wait and see what that weapon was before deciding on my course of action.
No. I grabbed the skinny bastards hand behind his back and smashed his head through the living room wall. (This is for the eagle-eyed among you, pre my wheelchair days!). As I outweighed him by about 50% ... his head went through the plasterboard wall and I imagine hurt quite a lot.
He later tried to claim that he 'only' had a plastic side table leg and that my use of force was unnecessary, and it wasn't self defense as he wasn't attacking me. It didn't wash, fortunately and he was out on licence in the first place so back he went.
But yep, in that moment if I'd had a gun at hand or in my hand, I might well have used that (but for the fact he was on top of my DP who was incapacitated in a beanbag chair on the floor!)
I fully believe when you enter someone elses property with a weapon and the intent to use it, wether that is to intimidate or actually physically use it, you lose certain rights the moment you enter the property.
I fervently hope the farmer has a good reason for having the weapon to hand, so that pre-meditated action is not a possibility. However sadly I doubt it, as a PP poster said, there are rules for firearms which make simply grabbing a loaded one an impossibility. Unless he happened to be cleaning his weapon in the same room the ammunition is kept at the time the burglars entered the property... which is unlikely!