The AR pistol vs a typical AR, the pistol is generally more concealable, it normally has very noticeably shorter barrel and more fun.Why would you want to do that?
What is to be gained?
If you do convert, we all here a promise to visit ye on visitation days.
Where i can buy a short barrel?
A little off topic, but when building an AR pistol, it's important that the stripped lower receiver be designated a pistol when it is first obtained from an FFL.