40 S&W is probably the most common caliber in law enforcement today. It bridges beautifully between the relatively anemic 9mm and the larger-framed and heavier recoiling 45ACP. It originated after the FBI commissioned a number of 10mm weapons, then found out that their "smaller" (women) agents had difficulty with the recoil- essentially that of a 357 magnum. Smith came up with the 10mm short- the 40 S&W.
You can find many easily-concealable 40 cal handguns on the market today.
As far as home defense, the one thing the shotgun has that little else can match is the intimidation factor. You REALLY don't want to shoot anyone. It's very expensive and time-consuming even if you prevail and don't have to go to prison. A pistol? You have to maybe shoot a couple holes through your own walls to get someone's attention. Who needs that. The shotgun? Everyone knows what that sound means.
You can find many easily-concealable 40 cal handguns on the market today.
As far as home defense, the one thing the shotgun has that little else can match is the intimidation factor. You REALLY don't want to shoot anyone. It's very expensive and time-consuming even if you prevail and don't have to go to prison. A pistol? You have to maybe shoot a couple holes through your own walls to get someone's attention. Who needs that. The shotgun? Everyone knows what that sound means.