Can't find a pic, but those familiar with the Sierra rack will know it has a casting "seam" down each side.

Not having looked inside one to see what's inside the "seam", but would it damage/weaken the rack casing if this outer "seam" were removed?

I'm going to chop the rack in the lathe and figured I might tidy the whole thing up while I'm there.

Its only a casting seam so you should have no problems the tube isn't under stress at any time