12ga or 20 ga. I personally use 12ga for home defense inside. I use my XCR setup for home defense if I think the fight will go outside. First grab is for the ole' dog eared double barrel.
If I had only one weapon for home defense it would be a shotgun.
Either a pump, semi auto or double barrel.
I am presently using my double barrel hammer gun loaded with #1 Buck per FBI minimum shot size recommendation. If we get to reloads, they are double ought. All my pumps are in the safe, with my rifles and carbines.
Best advice from the FBI for a fighting weapon:
The cogent advice by Urey Patrick of the FBI FTU should be routinely heeded:
“Experienced officers implicitly recognize...when potential violence is reasonably anticipated their preparations are characterized by obtaining as many shoulder weapons as possible.”
and
“...no law enforcement officer should ever plan to meet an expected attack armed only with a handgun.”
This applies to ALL HOME OWNERS TOO.
Old adage, you get caught in a fight with a handgun, you go to a fight with a shoulder weapon.
My personal felt adage, a handgun is for convenience and a shoulder arm is for fighting.
This is the advice from folks with experience in gun fighting. Amateurs rely on handguns when they could have had a shoulder weapon. First home defense weapon must be a rifle/carbine or shotgun.
Please don't rationalize.
Go figure.
Fred