As bertinjim says, the Columbus tubing is Aelle carbon-manganese alloy. I'm not sure, but I believe it was only available in Imperial diameters (25.4mm diameter top tube, 28.6mm down tube and seat tube, 31.7mm head tube). Here is catalog data sheet for the Aelle tubeset with diameters, wall thickness, butting, and uncut tube weights.

Aelle has straight gauge (non butted) main tubes with 0.8mm thick walls, so it's fairly heavy