One of my recent acquisitions is the latest Corto Prototype from Olympic, 612L-T. The rod has a tubular tip with 1.0 mm diameter right below the top guide. The rod is mind-blowing, steely, elegant... (I know these epithets can be overused, but I've fished a large number of top tier light game rods, so consider the source). What I'm trying to understand is this: how thin is the mandrel supposed to be at the top for rolling this thin of a tip? I know Graphiteleader are the experts in this field (hence the name) but I'm genuinely curios how far the rod engineering has come in recent years.
Thanks in advance for responses.