[prschmn]

Always found it curious methodology. One is assuming the area that the straightedge rests on is perfectly square to the longitudinal axis. Think about it-if that surface is out by even a couple
thou the deviation at the cam end is multiplied more that ten-fold. I;ve tried checking using a good square and referencing from the case half surface to the straightedge and it isnt always pretty but probably the simplest way to get some idea of alignment. Maybe I'm picking nits.