If they are from a gunsmith, they can be registered as pistols, the Taurus Judge is a .410 revolver, much easier to carry, more shots, probably cheaper. My 2 sawed offs cost me over 350 apiece, 40 years ago.
john
According to the ATF in order for it to be considered a pistol the bbl must be rifled, not a smooth bore. I have a old 16ga single bbl, that the stock was severly damaged on. so I cut it down. The ATF specs is 18in or longer bbl, and overall must be 28in or more. Mine has a 18.5in bbl and is 28.75 oveall. Mossberg makes a 12ga. pump with the same lengths as mine, in there Just In Case line. Remington makes a model 870 pump that has a 18in bbl., but has a regular stock. I know I have seem a pump with 18in bbl and a collasible stock, but don't recall who made them. You could buy a cheap used shotgunm and cut it down yourself and as long as it is in the ATF specs it will be legal.
To carry, I personally carry the Glock 26, I also have a 27 but prefer the 26 because with this light weight pistol and such a short grip, recoil affects your aim, I have clip extensions on one clip of each, gives me somewher to put my pinky as you can only get 2 fingers on the grip, I'd much druther have the stopping power of the 40cal in the 27, but the less recoil of the 9mm in the 26 makes it easier to hit what your shoting at, especially if your like me, getting old and your hands aren't as strong as they used to be. It doesn't matter what gun you use, if you can't hit what your aiming at.
In the house for personal defense I keep a Taurus Judge in my nightstand, with the first 2 chambers loaded with 410ga #4 shot and the other 3 with 45 Long Colt. Inside a house you are seldom going to need to shoot over 25 ft. And this revolver is ideal for that, besides you will only mess up one wall instead of going all the way throught the house, don't ask me how I know. I also keep a Glock 23 in the nightstand, the 40 cal in this heavier and longer gripped gun make it ideal. If I have time and can get to the gunsafe in the closet, I have all kinds of surprises for the perk.