Theres a reason Marstar doesn't sell the shorties....
They QC all their rifles before shipping them to Canada.... Apparently (from a post by Johnone) very few 18.5" rifles passed their "tests", so they didn't bring any in....
I myself am a little disappointed in the quality of the current crop of the shorties currently available.... I went through 12 rifles at the LGS (I was buying one for a friend), only 2 were what I consider "worth owning" (and then only after 3 hrs at the bench), 5 were unsafe to shoot or inoperable from the box.....
Marstar at least has a fairly exhaustive QC protocol in place to ensure the rifle is in spec and safe to operate....