You could probably tighten up groups if you measure overall length (OAL) to the ogive of the bullet rather than the tip. Length to the tip can vary as much as .026". Roughly, the ogive on the bullet is the point where the cylindrical portion of the bullet starts it's taper to the nose. Hornady sells a good tool for measuring OAL, it requires a modified case of the caliber being used. A sized case with two slits cut with a Dremel can also work though it's a little harder to remove the case w/o disturbing the measurement. With practice it too is a viable measuring option.