Naval gun rifling cutting bit.
https://diqn32j8nouaz.cloudfront.net...t_fullsize.jpg[/url]
Previously:
https://www.homemadetools.net/forum/...566#post139439
https://www.homemadetools.net/forum/...737#post152091
https://www.homemadetools.net/forum/...832#post163812
https://www.homemadetools.net/forum/...528#post162470
https://www.homemadetools.net/forum/...547#post128142
https://www.homemadetools.net/forum/...863#post144397
