Not long ago, my dog, who has had snake-avoidance training, started barking that "Boss, there's a snake out here and you'd better come tend to it" bark. As I went out the back door, I latched onto the Marlin 39M .22 rifle that is secreted there and quickly relocated the Western Diamondback rattler to snake heaven.
Most folks who have been raised in the country are quite familiar with a "back-door gun"—or kitchen-door gun, as some folks call it. It is that rifle or shotgun kept near the door to take care of all manner of critters that one might have to deal with. The caliber and gauge may change depending upon one's location and the size of said critters in question.
The thought occurs to me that this would not be a bad habit for urban dwellers to get into, either. Although in this case the dangerous critters we are now considering generally get around on two legs. Col. Jeff Cooper once wrote, "If you are reading this and can't put your hand on your defensive handgun, your training was wasted." And, yes, many of us wear a defensive handgun all of our waking hours. But, does everyone in the family adhere to this? When you open the door and look trouble square in the face, that gun in the upstairs bedroom on the nightstand is really not going to be much help.
In the days of the frontier, a rifle or shotgun was generally resting on a couple of nails above every external door in the cabin. And, while two nails above the door may not fit with the general décor of your modern home, the idea is still a sound one.
I can't tell you how and where to secret your door gun. Homes and situations are all so different. You should probably give some thought to keeping it concealed from casual observation. Having small children in the home will also limit your choices. However, I have seen tactically located book cases, cabinets and other pieces of furniture used to conceal the door gun. You've simply got to give it some thought and make the decision based upon your own situation and the layout of your home.
Nor do you have to go to great expense in acquiring a gun to keep by every external door in your house. Used pump shotguns cut to a manageable and legal barrel length, second-hand .30-30 Win. lever actions or the latest and best AR—the choice is really up to you and what fits your budget.
One thing is for sure—if you open your door to come face to face with evil, your rifle or shotgun will nearly always trump the knife, lead pipe or cheap handgun the current iterations of evil seem to prefer. Give it some thought.