How can I adjust the sensitivity of iron-sight aiming?

On my previous BL2 install I had an adjustment in one of the configuration files that made iron-sight aiming very near identical to the mouse sensitivity of hip-aiming, or at least a much lower reduction.

With 1-to-1 system level sensitivity and a low DPI (which I and many others prefer for FPS) the iron sight aim sensitivity is incredibly slow and needs adjustment, only after 30 minutes of searches I can’t find any mention of how I achieved this last time.

I’m pretty sure I found the thread on the BL2 forums but they appear to have been completely remodeled.