Jumpy volt gauge

My volt gauge seems to jump around a lot. 12 to 14 or so. All to the charging side but still jumpy.
I have new alternator, new regulator, new gauge, new belt and all new connections. Yep! It's a new build. Anyway, what are the possible causes of this or is it normal.
Oh yeah, battery, not so new but holds a charge, etc. Thanks as usual for any help. Dennis