When making a Hawken with a tapered barrel it's important to also taper the under rib in the opposite direction so the rod doesn't follow the line of the bottom of the barrel but is parallel with the bore.

This one has a tapered barrel and rib.
[Linked Image from live.staticflickr.com]100_1479 by .com/photos/156296479N08/]Steve Zihn, on [bleep]
[Linked Image from live.staticflickr.com]100_1483 by .com/photos/156296479N08/]Steve Zihn, on [bleep]