Don, I got notice of your post by e-mail. I had checked the preferences to notify me if someone had posted.
Let's see, that's something I have to think about.
1)The barrel I am working on has extreme swamp, so it's difficult to pop it in and out of the vise, and to get it level and square.
2)This will allow me to hold the sight for milling, filing, engraving, etc. without risk to the barrel itself.
3) extreme angles for milling are easily attained.
I guess I could make up more reasons.