drill rod?

[Triggernosis]

For my scope installation, I used a 1/4" rod help align my front Kokopelli alignment bar to the barrel. I used the straightest piece of rod that I could find at the local hardware store, inserted it with the "crown" up, and proceeded with the installation.
However, I've been told that a piece of "drill rod" would likely be straighter - is that what I need and where in the world am I likely to find it?
I can't imagine a 3' length of 1/4" stock being perfectly straight anyway.

[Black Diamond 408]

You can order it from MSC sales, or go to a machine-tool supply store. Drill rod is ground and polished, should be very straight. Totally differnt than mild steel hardware store rods.

Dave