Being from CT, I feel your pain. But I believe JMR40 is right. Manufacturers will produce magazines specific to certain state's requirements. I was surprised when I just picked up my Mini 14 it came with a 10 round mag, coincidentally, the maximum now allowed by CT law. Ruger's website says it comes with a 5 or 20 so I can only assume (if anyone knows differently, correct me) that they retooled specifically for CT. At least it seems that way.
It came with 2 and I bought a 3rd.