I briefly looked over the instuctions that came with the Brownells gauge and it seemed to be too much messing around when I could just use it horizontally without mounting it to anything.

I also think that when using the gauge vertically there is too much of a chance of applying pressure to the ball, causing an innaccurate reading. Any bit of movement on that will effect the reading by quite a lot.

Daryl,
Your bag of shot method sounds like a good solution for holding the barrels if one does not have a good vise to do the job.

My stock makers (or pattern makers) vise is great for this since both jaws are padded and they rotate independant of each other. Making the secure and safe holding of nearly any item easy.

B.Dudley