PCL tends not to scale, are you using a PS or PCL driver?
Have you tried the native driver and the Global Print driver?
I work with building plans where scale is important, and I've just noticed if I draw a 12" line and print it it comes out at about 11.95" instead. I had tried to print out some templates where the exact size mattered and found them all just a tiny bit too small.
I've gone over all the printing options and tried to print through a variety of programs. No scale is applied and if there is one it's set to 100%, not fit to page or anything like that. Printing directly from my CAD program produced these results, as well as printing from a PDF of the plans. When I printed the exact same file off our big old epson roll printer, it came out perfectly correct to scale, so it's not the file.
At this point I'm thinking I need to change something in the printer its self as it's applying this 98% scale to everything we print. Really looking for a solution to this.