Where do you clamp the jaws? On barrel extension or further forward on barrel shank?
Make a extension to go around the barrel extension, I drilled and tapped a set screw in mine to hold it in place and chuck it up between your headstock, This is assuming you have a spider on the back side of your headstock though.
Make a extension to go around the barrel extension, I drilled and tapped a set screw in mine to hold it in place and chuck it up between your headstock, This is assuming you have a spider on the back side of your headstock though.