AR pistols can get folks to scratching their heads asking the question, “Why?” Well, there are a couple very good reasons for their existence.
First, the law is more often much friendlier to pistols being carried concealed than rifles. As long as you can legally carry a concealed pistol, you can keep one on your person and in your vehicle in a variety of circumstances. On the other hand, rifles (especially loaded ones) are tightly regulated when it comes to concealment.
The second reason is AR pistols allow you to have an AR with a short barrel without the paperwork associated with having a short-barreled rifle. I like to invite “The Man” into my 
life as little as possible, so the lack of additional paperwork and forgoing the extra $200 in taxes (for the children, of course) are always appreciated.
Springfield Armory unveiled its lauded Saint AR a little over a year ago and has since expanded that line to include a lightweight model and this new pistol. The Saint pistol has a 7½-inch barrel and comes chambered in 5.56 NATO.
A 7½-inch barrel on a 5.56 pistol might cause some initial hesitation since the 5.56 is a rifle cartridge not designed for that short of a barrel. Likely concerns might be low muzzle velocity and excessive muzzle blast.
Black Hills’ excellent 50-grain VMAX load leaves the muzzle of this pistol at 2,408 feet per second (fps). This bullet will expand and fragment down to about 1,600 fps, due largely to the presence of the polymer tip and thin jacket. Black Hills’ load in this pistol will have good terminal performance out to just past 250 yards, which is about as far as I’d want to shoot it. That combination would also be