Based on my tests, the overall straightness is +/- .002 over a 3 ft length.
The testing method is as follows:
Place tube to be tested against an assumed straight edge. In my case a 4 ft level. Use a towel, folded multiple times to get enough pressure to hold the level and tube together, without introducing any additional measurement errors. Use a feeler guage to determine the maximum deflection from the level. Rotate the tube 60 degrees and repeat procedure. Continue until the tube has been measured in 6 places. Make sure to note if the maximum deflection occurs first in the middle and then 180 degrees later, at the ends.
Repeat above procedure for all barrel tubing in stock.
I know that there are a lot of things that might affect this test, therefore I know that the results are not necessarily valid. Please make of them what you will.
Sorry for the delay, but the measuring and data compliation took a while.