Once a paper copy goes outside, the scale is pretty much gone.Set a paper copy outside (especially in the South) and leave it for 30 minutes. Then check the scale. You will be surprised. Kinda like expecting a blur print to be to scale. (yea, right, rolling a sheet of paper around a glass cylinder while shinning a hot, bright light on it and blowing ammonia fumes on it will produce a scale copy.)
Only a few ways to get a true scaled copy. Contact photo print on 7mil stable base mylar or a correctly produced e-copy. I can burn you a scaled blue line using a flat bed exposure unit wit a glass lid and a big ole vaccuum pump, but once you walk outside, all bets are off.