So ? if a short barrel is that important to you pay the $200 instead of wasting $1150 on a gimmick.
To a lot of people it's not the $200, it's the fact that you now have a federally registered firearm. I know the argument is if you've ever filled out a 4473 or had a NICS background check you can be tracked if they want to. While true if you're a serious enough: collector, gun nut, enter your favorite term here, to pay to own something that .gov views as evil then you are on a even watchier watch list. I know a lot of people will say this is just paranoia but many will not take a chance. I know at least a few people who own many guns, 10 or more, and have never done a background check or filled out a 4473. They either got them through relatives or bought them in private sales. I always try to keep at least half my collection as private sale items that I never did a 4473 on. If it ever looks like they're going to come after all guns they will have to look very hard for some of mine. If they don't know you have them to begin with they'll be much harder to find.
As far as the original topic it is possible to be extremely precise with the pistol buffer tube and a good cheek weld. My issue is the 5.56 round is so anemic from a short barrel why bother.