You have an absolute right to carry on your own private property. You have absolutely zero right to carry on my private property.
If someone enters my domicile carrying a firearm and I do not know them, they're dead, period, bar none, end of discussion.
What will happen to me? Absolutely nothing. It's my private property, not theirs.
By the way, a fair number of wonderfully nice and well-armed gents who frequented this forum helped me move back in 2011. I treated them to a barbeque feast. Thanks, guys!
They were in and out of where I lived, back and forth, many times.
The key difference, there, Ghost1958, is I'd invited them. They had advanced permission, and I was very grateful for their assistance due to majorly bummed ankle. I needed all the help I could get!
I think you're mixing up business private property vs domicile private property. Businesses open to the public have an implied invitation of entry. If the sign says, "Open," then it's a written/posted invitation. If the sign says, "Closed," then it's a temporarily revoked invitation. A locked door is equivalent to a "closed" sign. Lacking any open/closed sign, if it looks, acts, and feels like a business and the door is unlocked, you're not trespassing if you enter, but you are trespassing if you do not leave the moment they say "we're closed" or "please leave."
Castle laws do not require me to ask or tell someone to leave. Without an express oral or written invitation, you're tresspassing the second you cross the threshold. B&E is equivalent to highly probable forfeiture of your own life.