So I bought a magmount CB antenna from Radio Schmack and just stuck it
in my front room for testing purposes, connected to a Midland 77-104 .
Using a borrowed handheld CB, range was barely half a mile (I live in a
city), but that could have just been the handheld.

I have the magmount up in the attic on a cookie sheet now. I don't have
the handheld anymore for testing purposes, but I have heard nothing on
channel 9 or 19 for several days, even after soliciting contacts a few
times. I've got someone with a CB about 6 miles away and I have a
freeway (i.e., truckers) also about 6 miles away... still can't make
contact with anyone.

Is 6 miles out of reach for an attic magmount? Do I need a better
ground plane or should I just give it up as a lost cause?